Fix unique keys and foreign key restore without stringified fetches

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

@@ -5646,7 +5646,7 @@ private function recreate_table_from_information_schema(
 		}
 
 		// 7. If foreign key constraints were enabled, verify and enable them.
-		if ( '1' === $pragma_foreign_keys ) {
+		if ( 1 === (int) $pragma_foreign_keys ) {
 			$this->execute_sqlite_query( 'PRAGMA foreign_key_check' );
 			$this->execute_sqlite_query( 'PRAGMA foreign_keys = ON' );
 		}
@@ -7138,7 +7138,7 @@ function ( $column ) {
 				}
 				$rows[] = sprintf( '  PRIMARY KEY (%s)', implode( ', ', $column_list ) );
 			} else {
-				$is_unique = '0' === $info['NON_UNIQUE'];
+				$is_unique = 0 === (int) $info['NON_UNIQUE'];
 
 				// Prefix the original index name with the table name.
 				// This is to avoid conflicting index names in SQLite.
@@ -7424,7 +7424,7 @@ private function get_mysql_create_table_statement( bool $table_is_temporary, str
 				$sql .= implode( ', ', array_map( $format_index_column, $constraint ) );
 				$sql .= ')';
 			} else {
-				$is_unique = '0' === $info['NON_UNIQUE'];
+				$is_unique = 0 === (int) $info['NON_UNIQUE'];
 
 				$sql  = sprintf(
 					'  %s%s%sKEY ',

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

@@ -5124,6 +5124,25 @@ public function dataLikeBinaryPatterns(): array {
 		);
 	}
 
+	/**
+	 * @dataProvider stringifyFetchesProvider
+	 */
+	public function testStringifyFetchesDoesNotAffectUniqueKeys( bool $stringify_fetches ): void {
+		$this->engine->setAttribute( PDO::ATTR_STRINGIFY_FETCHES, $stringify_fetches );
+
+		$this->assertQuery( 'CREATE TABLE t (id INT, email VARCHAR(50), UNIQUE KEY ue (email))' );
+		$result = $this->assertQuery( 'SHOW CREATE TABLE t' );
+		$this->assertStringContainsString( 'UNIQUE KEY `ue` (`email`)', $result[0]->{'Create Table'} );
+
+		// The unique key is kept when ALTER TABLE recreates the table.
+		$this->assertQuery( 'ALTER TABLE t ADD COLUMN name TEXT' );
+		$this->assertQuery( "INSERT INTO t (id, email) VALUES (1, 'a@example.com')" );
+
+		$this->expectException( 'WP_MySQL_On_SQLite_Exception' );
+		$this->expectExceptionMessage( 'UNIQUE constraint failed: t.email' );
+		$this->assertQuery( "INSERT INTO t (id, email) VALUES (2, 'a@example.com')" );
+	}
+
 	public function testUniqueConstraints() {
 		$this->assertQuery(
 			"CREATE TABLE _tmp_table (

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

@@ -884,7 +884,11 @@ public function testDropTemporaryTable(): void {
 		);
 	}
 
-	public function testAlterTableAddColumn(): void {
+	/**
+	 * @dataProvider stringifyFetchesProvider
+	 */
+	public function testAlterTableAddColumn( bool $stringify_fetches ): void {
+		$this->driver->setAttribute( PDO::ATTR_STRINGIFY_FETCHES, $stringify_fetches );
 		$this->driver->query( 'CREATE TABLE t (id INT)' );
 		$this->assertQuery(
 			array(
@@ -915,6 +919,13 @@ public function testAlterTableAddColumn(): void {
 		);
 	}
 
+	public function stringifyFetchesProvider(): array {
+		return array(
+			'stringification disabled' => array( false ),
+			'stringification enabled'  => array( true ),
+		);
+	}
+
 	public function testAlterTableAddColumnWithNotNull(): void {
 		$this->driver->query( 'CREATE TABLE t (id INT)' );
 		$this->assertQuery(