Skip unmatched rows in multi-table DELETE with outer JOINs

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

@@ -2886,12 +2886,27 @@ private function execute_delete_statement( WP_Parser_Node $node ): void {
 			$affected_rows = 0;
 			if ( count( $ids ) > 0 ) {
 				foreach ( $table_aliases as $table ) {
+					/*
+					 * With an outer JOIN, a table may have no matching row for
+					 * some of the selected rows. Its ROWID is NULL for those rows,
+					 * and there is nothing to delete from the table for them.
+					 */
+					$rowids = array_filter(
+						array_column( $ids, "{$table}_rowid" ),
+						function ( $rowid ) {
+							return null !== $rowid;
+						}
+					);
+					if ( count( $rowids ) === 0 ) {
+						continue;
+					}
+
 					$stmt           = $this->execute_sqlite_query(
 						sprintf(
 							'DELETE FROM %s AS %s WHERE rowid IN ( %s )',
 							$this->quote_sqlite_identifier( $alias_map[ $table ] ),
 							$this->quote_sqlite_identifier( $table ),
-							implode( ', ', array_column( $ids, "{$table}_rowid" ) )
+							implode( ', ', $rowids )
 						)
 					);
 					$affected_rows += $stmt->rowCount();

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

@@ -6200,6 +6200,44 @@ public function testTranslatesComplexDelete() {
 		);
 	}
 
+	public function testMultiTableDeleteWithLeftJoinSkipsUnmatchedRows(): void {
+		$this->assertQuery( 'CREATE TABLE p (id INT PRIMARY KEY, type TEXT)' );
+		$this->assertQuery( 'CREATE TABLE pm (id INT PRIMARY KEY, post_id INT)' );
+		$this->assertQuery( "INSERT INTO p VALUES (1, 'revision'), (2, 'revision'), (3, 'post')" );
+		$this->assertQuery( 'INSERT INTO pm VALUES (1, 1), (2, 1), (3, 3)' );
+
+		// Post 2 has no metadata, so its "pm" ROWID is NULL.
+		$result = $this->assertQuery(
+			"DELETE p, pm FROM p LEFT JOIN pm ON pm.post_id = p.id WHERE p.type = 'revision'"
+		);
+		$this->assertSame( 4, $result );
+
+		$result = $this->assertQuery( 'SELECT id FROM p ORDER BY id' );
+		$this->assertSame( array( '3' ), array_column( $result, 'id' ) );
+		$result = $this->assertQuery( 'SELECT id FROM pm ORDER BY id' );
+		$this->assertSame( array( '3' ), array_column( $result, 'id' ) );
+	}
+
+	public function testMultiTableDeleteWithLeftJoinAndNoMatchesInJoinedTable(): void {
+		$this->assertQuery( 'CREATE TABLE p (id INT PRIMARY KEY)' );
+		$this->assertQuery( 'CREATE TABLE pm (id INT PRIMARY KEY, post_id INT)' );
+		$this->assertQuery( 'INSERT INTO p VALUES (1), (2), (3)' );
+		$this->assertQuery( 'INSERT INTO pm VALUES (1, 3)' );
+
+		// Only the joined table is a target, and it has no matching rows.
+		$result = $this->assertQuery( 'DELETE pm FROM p LEFT JOIN pm ON pm.post_id = p.id WHERE p.id < 3' );
+		$this->assertSame( 0, $result );
+
+		// Both tables are targets, and the joined table has no matching rows.
+		$result = $this->assertQuery( 'DELETE p, pm FROM p LEFT JOIN pm ON pm.post_id = p.id WHERE p.id < 3' );
+		$this->assertSame( 2, $result );
+
+		$result = $this->assertQuery( 'SELECT id FROM p ORDER BY id' );
+		$this->assertSame( array( '3' ), array_column( $result, 'id' ) );
+		$result = $this->assertQuery( 'SELECT id FROM pm ORDER BY id' );
+		$this->assertSame( array( '1' ), array_column( $result, 'id' ) );
+	}
+
 	public function testDeleteReturnsZeroAffectedRowsWhenNoMatchingRows() {
 		$this->assertQuery( 'CREATE TABLE t (id INT)' );
 		$this->assertQuery( 'INSERT INTO t (id) VALUES (1)' );