diff --git a/.phpstan-dba-mysqli.cache b/.phpstan-dba-mysqli.cache
index e36d9741e..ea4c79acc 100644
--- a/.phpstan-dba-mysqli.cache
+++ b/.phpstan-dba-mysqli.cache
@@ -926,6 +926,78 @@
         )),
       ),
     ),
+    'SELECT
+        CASE
+            WHEN freigabe1u1 > 50 THEN \'big-one\'
+            WHEN freigabe1u1 = 50 THEN \'normal\'
+            ELSE freigabe1u1
+        END as val from ada' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'val\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'val',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\StringType::__set_state(array(
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'val',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\StringType::__set_state(array(
+            )),
+            1 => 
+            PHPStan\Type\StringType::__set_state(array(
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
     'SELECT * FROM ada' => 
     array (
       'result' => 
@@ -10230,6 +10302,758 @@
         )),
       ),
     ),
+    'SELECT sum(akid) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\IntersectionType::__set_state(array(
+                 'sortedTypes' => false,
+                 'types' => 
+                array (
+                  0 => 
+                  PHPStan\Type\StringType::__set_state(array(
+                  )),
+                  1 => 
+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(c_double) as sum from typemix' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\FloatType::__set_state(array(
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(eladaid) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\IntersectionType::__set_state(array(
+                 'sortedTypes' => false,
+                 'types' => 
+                array (
+                  0 => 
+                  PHPStan\Type\StringType::__set_state(array(
+                  )),
+                  1 => 
+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(freigabe1u1) as sum from ada' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\IntersectionType::__set_state(array(
+                 'sortedTypes' => false,
+                 'types' => 
+                array (
+                  0 => 
+                  PHPStan\Type\StringType::__set_state(array(
+                  )),
+                  1 => 
+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(freigabe1u1) as sum from ak' => 
+    array (
+      'error' => 
+      staabm\PHPStanDba\Error::__set_state(array(
+         'message' => 'Unknown column \'freigabe1u1\' in \'field list\'',
+         'code' => 1054,
+      )),
+    ),
+    'SELECT sum(null) as sum from ada' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\FloatType::__set_state(array(
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(null) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\FloatType::__set_state(array(
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
     'SELECT ucase(c_varbinary25) as field from typemix' => 
     array (
       'result' => 
diff --git a/src/SqlAst/QueryScope.php b/src/SqlAst/QueryScope.php
index 62de1c29a..9a9ea7ce4 100644
--- a/src/SqlAst/QueryScope.php
+++ b/src/SqlAst/QueryScope.php
@@ -59,6 +59,7 @@ public function __construct(Table $fromTable, array $joinedTables)
             new InstrReturnTypeExtension(),
             new StrCaseReturnTypeExtension(),
             new AvgReturnTypeExtension(),
+            new SumReturnTypeExtension(),
             new IsNullReturnTypeExtension(),
             new AbsReturnTypeExtension(),
             new RoundReturnTypeExtension(),
diff --git a/src/SqlAst/SumReturnTypeExtension.php b/src/SqlAst/SumReturnTypeExtension.php
new file mode 100644
index 000000000..596f68d2b
--- /dev/null
+++ b/src/SqlAst/SumReturnTypeExtension.php
@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace staabm\PHPStanDba\SqlAst;
+
+use PHPStan\Type\FloatType;
+use PHPStan\Type\IntegerType;
+use PHPStan\Type\NullType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use SqlFtw\Sql\Expression\BuiltInFunction;
+use SqlFtw\Sql\Expression\FunctionCall;
+
+final class SumReturnTypeExtension implements QueryFunctionReturnTypeExtension
+{
+    public function isFunctionSupported(FunctionCall $expression): bool
+    {
+        return \in_array($expression->getFunction()->getName(), [BuiltInFunction::SUM], true);
+    }
+
+    public function getReturnType(FunctionCall $expression, QueryScope $scope): ?Type
+    {
+        $args = $expression->getArguments();
+
+        if (1 !== \count($args)) {
+            return null;
+        }
+
+        $argType = $scope->getType($args[0]);
+        if ($argType->isNull()->yes()) {
+            return new NullType();
+        }
+
+        $containsNull = TypeCombinator::containsNull($argType);
+        $argType = TypeCombinator::removeNull($argType);
+        if ($argType->isInteger()->yes()) {
+            // sum(IntegerRange) is a unbound integer
+            $result = new IntegerType();
+        } elseif ($argType->isFloat()->yes()) {
+            $result = new FloatType();
+        } else {
+            $result = $argType;
+        }
+
+        if ($containsNull) {
+            $result = TypeCombinator::addNull($result);
+        }
+
+        return $result;
+    }
+}
diff --git a/tests/default/config/.phpunit-phpstan-dba-mysqli.cache b/tests/default/config/.phpunit-phpstan-dba-mysqli.cache
index e90705429..8e6d1199b 100644
--- a/tests/default/config/.phpunit-phpstan-dba-mysqli.cache
+++ b/tests/default/config/.phpunit-phpstan-dba-mysqli.cache
@@ -239,6 +239,78 @@
         )),
       ),
     ),
+    'SELECT
+        CASE
+            WHEN freigabe1u1 > 50 THEN \'big-one\'
+            WHEN freigabe1u1 = 50 THEN \'normal\'
+            ELSE freigabe1u1
+        END as val from ada' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'val\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'val',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\StringType::__set_state(array(
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'val',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\StringType::__set_state(array(
+            )),
+            1 => 
+            PHPStan\Type\StringType::__set_state(array(
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
     'SELECT * FROM ada' => 
     array (
       'result' => 
@@ -16350,6 +16422,641 @@ FROM ada' =>
         )),
       ),
     ),
+    'SELECT sum(akid) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\IntersectionType::__set_state(array(
+                 'sortedTypes' => false,
+                 'types' => 
+                array (
+                  0 => 
+                  PHPStan\Type\StringType::__set_state(array(
+                  )),
+                  1 => 
+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(c_double) as sum from typemix' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\FloatType::__set_state(array(
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(eladaid) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\IntersectionType::__set_state(array(
+                 'sortedTypes' => false,
+                 'types' => 
+                array (
+                  0 => 
+                  PHPStan\Type\StringType::__set_state(array(
+                  )),
+                  1 => 
+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(freigabe1u1) as sum from ada' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\IntersectionType::__set_state(array(
+                 'sortedTypes' => false,
+                 'types' => 
+                array (
+                  0 => 
+                  PHPStan\Type\StringType::__set_state(array(
+                  )),
+                  1 => 
+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(null) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\FloatType::__set_state(array(
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
     'SELECT ucase(c_varbinary25) as field from typemix' => 
     array (
       'result' => 
diff --git a/tests/default/config/.phpunit-phpstan-dba-pdo-mysql.cache b/tests/default/config/.phpunit-phpstan-dba-pdo-mysql.cache
index c4dd815dd..6f39545d9 100644
--- a/tests/default/config/.phpunit-phpstan-dba-pdo-mysql.cache
+++ b/tests/default/config/.phpunit-phpstan-dba-pdo-mysql.cache
@@ -239,6 +239,78 @@
         )),
       ),
     ),
+    'SELECT
+        CASE
+            WHEN freigabe1u1 > 50 THEN \'big-one\'
+            WHEN freigabe1u1 = 50 THEN \'normal\'
+            ELSE freigabe1u1
+        END as val from ada' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'val\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'val',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\StringType::__set_state(array(
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'val',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\StringType::__set_state(array(
+            )),
+            1 => 
+            PHPStan\Type\StringType::__set_state(array(
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
     'SELECT * FROM ada' => 
     array (
       'result' => 
@@ -15351,6 +15423,502 @@ FROM ada' =>
         )),
       ),
     ),
+    'SELECT sum(akid) as sum from ak' => 
+    array (
+      'result' => 
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+                 'objectType' => NULL,
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+                 'value' => 'sum',
+                 'isClassString' => false,
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+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
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+             'cachedDescriptions' => 
+            array (
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+             'types' => 
+            array (
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+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
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+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(c_double) as sum from typemix' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
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+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
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+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\FloatType::__set_state(array(
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(eladaid) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\IntersectionType::__set_state(array(
+                 'sortedTypes' => false,
+                 'types' => 
+                array (
+                  0 => 
+                  PHPStan\Type\StringType::__set_state(array(
+                  )),
+                  1 => 
+                  PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                  )),
+                ),
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\IntersectionType::__set_state(array(
+                   'sortedTypes' => false,
+                   'types' => 
+                  array (
+                    0 => 
+                    PHPStan\Type\StringType::__set_state(array(
+                    )),
+                    1 => 
+                    PHPStan\Type\Accessory\AccessoryNumericStringType::__set_state(array(
+                    )),
+                  ),
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
+    'SELECT sum(null) as sum from ak' => 
+    array (
+      'result' => 
+      array (
+        5 => 
+        PHPStan\Type\Constant\ConstantArrayType::__set_state(array(
+           'keyType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => true,
+             'cachedDescriptions' => 
+            array (
+              2 => '0|\'sum\'',
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+                 'value' => 0,
+              )),
+              1 => 
+              PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+                 'objectType' => NULL,
+                 'arrayKeyType' => NULL,
+                 'value' => 'sum',
+                 'isClassString' => false,
+              )),
+            ),
+             'normalized' => false,
+          )),
+           'itemType' => 
+          PHPStan\Type\UnionType::__set_state(array(
+             'sortedTypes' => false,
+             'cachedDescriptions' => 
+            array (
+            ),
+             'types' => 
+            array (
+              0 => 
+              PHPStan\Type\FloatType::__set_state(array(
+              )),
+              1 => 
+              PHPStan\Type\NullType::__set_state(array(
+              )),
+            ),
+             'normalized' => true,
+          )),
+           'allArrays' => NULL,
+           'nextAutoIndexes' => 
+          array (
+            0 => 1,
+          ),
+           'keyTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\Constant\ConstantStringType::__set_state(array(
+               'objectType' => NULL,
+               'arrayKeyType' => NULL,
+               'value' => 'sum',
+               'isClassString' => false,
+            )),
+            1 => 
+            PHPStan\Type\Constant\ConstantIntegerType::__set_state(array(
+               'value' => 0,
+            )),
+          ),
+           'valueTypes' => 
+          array (
+            0 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+            1 => 
+            PHPStan\Type\UnionType::__set_state(array(
+               'sortedTypes' => false,
+               'cachedDescriptions' => 
+              array (
+              ),
+               'types' => 
+              array (
+                0 => 
+                PHPStan\Type\FloatType::__set_state(array(
+                )),
+                1 => 
+                PHPStan\Type\NullType::__set_state(array(
+                )),
+              ),
+               'normalized' => true,
+            )),
+          ),
+           'optionalKeys' => 
+          array (
+          ),
+           'isList' => false,
+        )),
+      ),
+    ),
     'SELECT ucase(c_varbinary25) as field from typemix' => 
     array (
       'result' => 
diff --git a/tests/default/data/sql-ast-narrowing.php b/tests/default/data/sql-ast-narrowing.php
index 0f4ef4151..daeea4ada 100644
--- a/tests/default/data/sql-ast-narrowing.php
+++ b/tests/default/data/sql-ast-narrowing.php
@@ -264,4 +264,19 @@ public function round(PDO $pdo): void
         $stmt = $pdo->query('SELECT round(1.12, 1) as abs from ak');
         assertType('PDOStatement<array{abs: float|int, 0: float|int}>', $stmt);
     }
+
+    public function sum(PDO $pdo): void
+    {
+        $stmt = $pdo->query('SELECT sum(null) as sum from ak');
+        assertType('PDOStatement<array{sum: null, 0: null}>', $stmt);
+
+        $stmt = $pdo->query('SELECT sum(akid) as sum from ak');
+        assertType('PDOStatement<array{sum: int, 0: int}>', $stmt);
+
+        $stmt = $pdo->query('SELECT sum(eladaid) as sum from ak');
+        assertType('PDOStatement<array{sum: int|null, 0: int|null}>', $stmt);
+
+        $stmt = $pdo->query('SELECT sum(c_double) as sum from typemix');
+        assertType('PDOStatement<array{sum: float, 0: float}>', $stmt);
+    }
 }