Bug #73299 [Com]: Cannot change db with "use another_db" sql query

Edit report at https://bugs.php.net/bug.php?id=73299&edit=1 ID: 73299 Comment by: gmblar+php at gmail dot com Reported by: lubomir dot cvrk at webnode dot com Summary: Cannot change db with "use another_db" sql query Status: Open Type: Bug Package: PDO MySQL Operating System: Linux, Windows PHP Version: 5.6.26 Block user comment: N Private report: N New Comment: $pdo = new PDO('mysql:host=example.com', 'username', 'password', [ PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE, PDO::ATTR_EMULATE_PREPARES => FALSE ]); // Test 1 $pdo->query("USE database;"); // Test 2 $statement = $pdo->prepare("USE database;"); $statement->execute(); // Test 3 $statement = $pdo->prepare("USE database;", [ PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE ]); $statement->execute(); All tests failed (even with ";dbname=database" in the dsn). If PDO::ATTR_EMULATE_PREPARES is set to FALSE and with any use-query with: PHP Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute. tested with: PHP 7.1.0 (cli) (built: Dec 5 2016 22:54:50) ( NTS ) Copyright (c) 1997-2016 The PHP Group Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies Previous Comments: ------------------------------------------------------------------------ [2016-10-12 05:36:08] lubomir dot cvrk at webnode dot com Description: ------------ When \PDO::ATTR_EMULATE_PREPARES == false, and the initial connection is created with "some_db" context, the PDO is unable to run the query for changing the database (use another_db) and returns an error: Array ( [0] => HY000 [1] => 2014 [2] => Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute. ) Test script: --------------- function test_pdo($prepares) { echo 'Testing PDO with \PDO::ATTR_EMULATE_PREPARES=' . ($prepares ? 'true' : 'false') . "\n\n"; $options[\PDO::ATTR_EMULATE_PREPARES] = $prepares; $db = new PDO('mysql:host=some.host.net;dbname=some_db;charset=utf8','user','password',$options); $result = $db->query('use ms_system'); echo 'After PDO::query(use another_db): '; echo $result === false ? 'PDO ERROR' : 'PDO is OK'; echo "\n"; $stmt = $db->prepare('use ms_system'); $result = $stmt->execute(); echo 'After PDO::prepare(use another_db); PDO::execute(): '; if ($result === false) { echo 'PDO ERROR - ' . print_r($stmt->errorInfo(), true); } else { echo 'PDO is OK'; } echo "\n---------------------------------------------------\n\n"; } echo '<xmp>'; test_pdo(true); test_pdo(false); Expected result: ---------------- <xmp>Testing PDO with \PDO::ATTR_EMULATE_PREPARES=true After PDO::query(use another_db): PDO is OK After PDO::prepare(use another_db); PDO::execute(): PDO is OK --------------------------------------------------- Testing PDO with \PDO::ATTR_EMULATE_PREPARES=false After PDO::query(use another_db): PDO is OK After PDO::prepare(use another_db); PDO::execute(): PDO is OK --------------------------------------------------- ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=73299&edit=1