Fix temporary table lookup without stringified fetches and with a different case

packages/mysql-on-sqlite/src/sqlite/class-wp-mysql-on-sqlite.php

@@ -5466,8 +5466,8 @@ private function translate_table_ref( WP_Parser_Node $node ): string {
 				}
 			}
 
-			$table_is_temporary = $this->information_schema_builder->temporary_table_exists( $table_name );
-			$sqlite_table_name  = $this->information_schema_builder->get_table_name( $table_is_temporary, $table_name );
+			// Temporary tables are not listed in the information schema.
+			$sqlite_table_name = $this->information_schema_builder->get_table_name( false, $table_name );
 
 			// We need to fetch the SQLite column information, because the information
 			// schema tables don't contain records for the information schema itself.

packages/mysql-on-sqlite/src/sqlite/class-wp-sqlite-information-schema-builder.php

@@ -381,12 +381,16 @@ public function temporary_table_exists( string $table_name ): bool {
 		/*
 		 * We could search in the "{$this->temporary_table_prefix}tables" table,
 		 * but it may not exist yet, so using "sqlite_temp_master" is simpler.
+		 *
+		 * The name is matched case-insensitively, as it is in the information
+		 * schema tables. The fetched value is not compared to a string, because
+		 * PDO SQLite returns native types when fetches are not stringified.
 		 */
 		$stmt = $this->connection->query(
-			"SELECT 1 FROM sqlite_temp_master WHERE type = 'table' AND name = ?",
+			"SELECT 1 FROM sqlite_temp_master WHERE type = 'table' AND name = ? COLLATE NOCASE",
 			array( $table_name )
 		);
-		return $stmt->fetchColumn() === '1';
+		return false !== $stmt->fetchColumn();
 	}
 
 	/**

packages/mysql-on-sqlite/tests/WP_MySQL_On_SQLite_Tests.php

@@ -5842,7 +5842,31 @@ public function getInformationSchemaIsReadonlyWithUseTestData(): array {
 		);
 	}
 
-	public function testTemporaryTableHasPriorityOverStandardTable(): void {
+	public function testTemporaryTableIsFoundByDifferentlyCasedName(): void {
+		// Create a standard and a temporary table with the same name.
+		$this->assertQuery( 'CREATE TABLE t (a INT)' );
+		$this->assertQuery( 'CREATE TEMPORARY TABLE t (b INT)' );
+
+		// ALTER TABLE will use the temporary table.
+		$this->assertQuery( 'ALTER TABLE T ADD COLUMN c INT' );
+		$result = $this->assertQuery( 'SHOW COLUMNS FROM T' );
+		$this->assertCount( 2, $result );
+		$this->assertEquals( 'b', $result[0]->Field );
+		$this->assertEquals( 'c', $result[1]->Field );
+
+		// DROP TABLE will remove the temporary table and keep the standard table.
+		$this->assertQuery( 'DROP TABLE T' );
+		$result = $this->assertQuery( 'SHOW COLUMNS FROM T' );
+		$this->assertCount( 1, $result );
+		$this->assertEquals( 'a', $result[0]->Field );
+	}
+
+	/**
+	 * @dataProvider stringifyFetchesProvider
+	 */
+	public function testTemporaryTableHasPriorityOverStandardTable( bool $stringify_fetches ): void {
+		$this->engine->setAttribute( PDO::ATTR_STRINGIFY_FETCHES, $stringify_fetches );
+
 		// Create a standard and a temporary table with the same name.
 		$this->assertQuery( 'CREATE TABLE t (a INT, INDEX ia(a))' );
 		$this->assertQuery( 'CREATE TEMPORARY TABLE t (b INT, INDEX ib(b))' );
@@ -5883,6 +5907,7 @@ public function testTemporaryTableHasPriorityOverStandardTable(): void {
 		// First DROP TABLE removes the temporary table.
 		$this->assertQuery( 'DROP TABLE t' );
 		$result = $this->assertQuery( 'SHOW COLUMNS FROM t' );
+		$this->assertCount( 1, $result );
 		$this->assertEquals( 'a', $result[0]->Field );
 
 		// Second DROP TABLE removes the standard table.
@@ -5892,6 +5917,38 @@ public function testTemporaryTableHasPriorityOverStandardTable(): void {
 		$result = $this->assertQuery( 'SHOW COLUMNS FROM t' );
 	}
 
+	public function stringifyFetchesProvider(): array {
+		return array(
+			'stringification disabled' => array( false ),
+			'stringification enabled'  => array( true ),
+		);
+	}
+
+	public function testTemporaryTableNamedLikeInformationSchemaTable(): void {
+		// Create a standard table and temporary tables named like information schema tables.
+		$this->assertQuery( 'CREATE TABLE t (a INT, INDEX ia(a))' );
+		$this->assertQuery( 'CREATE TEMPORARY TABLE tables (b INT)' );
+		$this->assertQuery( 'CREATE TEMPORARY TABLE COLUMNS (b INT)' );
+		$this->assertQuery( 'CREATE TEMPORARY TABLE Statistics (b INT, INDEX ib(b))' );
+
+		// The information schema shows the standard table only.
+		$table_names = "('t', 'tables', 'columns', 'statistics')";
+
+		$result = $this->assertQuery( "SELECT table_name FROM information_schema.tables WHERE table_name IN $table_names" );
+		$this->assertCount( 1, $result );
+		$this->assertEquals( 't', $result[0]->TABLE_NAME );
+
+		$result = $this->assertQuery( "SELECT table_name, column_name FROM information_schema.columns WHERE table_name IN $table_names" );
+		$this->assertCount( 1, $result );
+		$this->assertEquals( 't', $result[0]->TABLE_NAME );
+		$this->assertEquals( 'a', $result[0]->COLUMN_NAME );
+
+		$result = $this->assertQuery( "SELECT table_name, index_name FROM information_schema.statistics WHERE table_name IN $table_names" );
+		$this->assertCount( 1, $result );
+		$this->assertEquals( 't', $result[0]->TABLE_NAME );
+		$this->assertEquals( 'ia', $result[0]->INDEX_NAME );
+	}
+
 	public function testStrictSqlModeNullWithoutDefault(): void {
 		$this->assertQuery( "SET SESSION sql_mode = 'STRICT_ALL_TABLES'" );
 

packages/mysql-on-sqlite/tests/WP_MySQL_On_SQLite_Translation_Tests.php

@@ -2157,7 +2157,7 @@ private function assertQuery( $expected, string $query ): void {
 			array_filter(
 				$executed_queries,
 				function ( $query ) {
-					return "SELECT 1 FROM sqlite_temp_master WHERE type = 'table' AND name = ?" !== $query;
+					return "SELECT 1 FROM sqlite_temp_master WHERE type = 'table' AND name = ? COLLATE NOCASE" !== $query;
 				}
 			)
 		);