[#82] Added FROM clause to update builder

update.go

@@ -21,6 +21,7 @@ type updateData struct {
 	Limit             string
 	Offset            string
 	Suffixes          exprs
+	From              Sqlizer
 }
 
 type setClause struct {
@@ -230,3 +231,9 @@ func (b UpdateBuilder) Offset(offset uint64) UpdateBuilder {
 func (b UpdateBuilder) Suffix(sql string, args ...interface{}) UpdateBuilder {
 	return builder.Append(b, "Suffixes", Expr(sql, args...)).(UpdateBuilder)
 }
+
+// From adds FROM clause to the query
+// FROM is valid construct in postgresql only.
+func (b UpdateBuilder) From(from string) UpdateBuilder {
+	return builder.Set(b, "From", newPart(from)).(UpdateBuilder)
+}

update_test.go

@@ -66,3 +66,9 @@ func TestUpdateBuilderNoRunner(t *testing.T) {
 	_, err := b.Exec()
 	assert.Equal(t, RunnerNotSet, err)
 }
+
+func TestUpdateBuilderFromClause(t *testing.T) {
+	sql, _, err := Update("employees").Set("sales_count", 100).From("accounts").Where("accounts.name = ?", "ACME").ToSql()
+	assert.NoError(t, err)
+	assert.Equal(t, "UPDATE employees SET sales_count = ? WHERE accounts.name = ?", sql)
+}