Represent query type as enum in QueryBuilder

UPGRADE.md

@@ -299,8 +299,12 @@ The following `QueryBuilder` methods have been removed:
 
 The following `QueryBuilder` constants have been removed:
 
-1. `STATE_DIRTY`,
-2. `STATE_CLEAN`.
+1. `SELECT`,
+2. `DELETE`,
+3. `UPDATE`,
+4. `INSERT`,
+5. `STATE_DIRTY`,
+6. `STATE_CLEAN`.
 
 ## BC BREAK: Removed the `Constraint` interface.
 

src/Query/QueryBuilder.php

@@ -37,26 +37,6 @@
  */
 class QueryBuilder
 {
-    /**
-     * @deprecated
-     */
-    final public const SELECT = 0;
-
-    /**
-     * @deprecated
-     */
-    final public const DELETE = 1;
-
-    /**
-     * @deprecated
-     */
-    final public const UPDATE = 2;
-
-    /**
-     * @deprecated
-     */
-    final public const INSERT = 3;
-
     /**
      * The complete SQL string for this query.
      */
@@ -79,7 +59,7 @@ class QueryBuilder
     /**
      * The type of query this is. Can be select, update or delete.
      */
-    private int $type = self::SELECT;
+    private QueryType $type = QueryType::SELECT;
 
     /**
      * The index of the first result to retrieve.
@@ -348,10 +328,10 @@ public function getSQL(): string
         }
 
         $sql = match ($this->type) {
-            self::INSERT => $this->getSQLForInsert(),
-            self::DELETE => $this->getSQLForDelete(),
-            self::UPDATE => $this->getSQLForUpdate(),
-            default => $this->getSQLForSelect(),
+            QueryType::INSERT => $this->getSQLForInsert(),
+            QueryType::DELETE => $this->getSQLForDelete(),
+            QueryType::UPDATE => $this->getSQLForUpdate(),
+            QueryType::SELECT => $this->getSQLForSelect(),
         };
 
         $this->sql = $sql;
@@ -539,7 +519,7 @@ public function getMaxResults(): ?int
      */
     public function select(string ...$expressions): self
     {
-        $this->type = self::SELECT;
+        $this->type = QueryType::SELECT;
 
         if (count($expressions) < 1) {
             return $this;
@@ -591,7 +571,7 @@ public function distinct(): self
      */
     public function addSelect(string $expression, string ...$expressions): self
     {
-        $this->type = self::SELECT;
+        $this->type = QueryType::SELECT;
 
         $this->select = array_merge($this->select, [$expression], $expressions);
 
@@ -617,7 +597,7 @@ public function addSelect(string $expression, string ...$expressions): self
      */
     public function delete(string $table): self
     {
-        $this->type = self::DELETE;
+        $this->type = QueryType::DELETE;
 
         $this->table = $table;
 
@@ -643,7 +623,7 @@ public function delete(string $table): self
      */
     public function update(string $table): self
     {
-        $this->type = self::UPDATE;
+        $this->type = QueryType::UPDATE;
 
         $this->table = $table;
 
@@ -673,7 +653,7 @@ public function update(string $table): self
      */
     public function insert(string $table): self
     {
-        $this->type = self::INSERT;
+        $this->type = QueryType::INSERT;
 
         $this->table = $table;
 

src/Query/QueryType.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\DBAL\Query;
+
+/**
+ * @internal
+ */
+enum QueryType
+{
+    case SELECT;
+    case DELETE;
+    case UPDATE;
+    case INSERT;
+}