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[2020-07-18 13:46 UTC] brian at statagroup dot com
Description:
------------
Hypothetically there is no difference between what these two examples do (except for the introduction of a variable).
ex1.
$statement = $connection->prepare($sql);
$statement->execute();
ex2.
$connection->prepare($sql)->execute();
In practice, the first example fails under specific and reproducible conditions.
Test script:
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I've created a full demonstration of the issue on github using PHP docker images.
https://github.com/Incognito/php-pdo_mysql-defect-evidence
$connection = new PDO('mysql:host=db;port=3306;dbname=mysql', 'root', 'example', []);
$connection->prepare('DROP TABLE IF EXISTS pdo_bug_test;')->execute();
$connection->prepare('CREATE TABLE pdo_bug_test (value1 VARCHAR(10), value2 INT);')->execute();
$connection->beginTransaction();
$sql = 'INSERT INTO pdo_bug_test (value1, value2) VALUES (1, 2);';
$sql .= 'INSERT INTO pdo_bug_test (value1, value2) VALUES (3, 4);';
$statement = $connection->prepare($sql); $statement->execute();
$result = $connection->commit();
Expected result:
----------------
I expect the two examples to work exactly the same. In practice this difference is introduced on versions of PHP which contain commit 51cdd3dc50af88461d83aec0fac1dca83400b58f .
This means 5.6 works the same for both examples. However, 7.0.23, 7.1.9, and 7.2.0 are the releases that introduce this change in the git tree.
PatchesPull RequestsHistoryAllCommentsChangesGit/SVN commits
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Last updated: Thu Oct 30 05:00:01 2025 UTC |
Thank for reporting! This is not related to commit 51cdd3d[1], tough. This commit just fixed the return value, so that ::commit() properly returns false for versions which have that fix. And actually, this issue is not particularly related to transactions at all. Consider the following modified reproduce script: <?php // connect and create table as before, but also set PDO::ERRMODE_WARNING $sql = 'INSERT INTO pdo_bug_test (value1, value2) VALUES (1, 2);'; $sql .= 'INSERT INTO pdo_bug_test (value1, value2) VALUES (3, 4);'; $statement = $connection->prepare($sql); $statement->execute(); print_r($connection->query('SELECT * FROM pdo_bug_test')->fetchAll()); ?> That raises the following warning: Warning: PDO::query(): 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. in %s on line %d The failing ::commit() doesn't show that warning due to bug #66528. To make the code work as desired (without the need for buffered queries), you'd need to call $statement->nextRowset() after executing the multi-statement (or to destroy the PDOStatement, what would do that implicitely; that is why the code without the variable works). I tend to change this ticket to doc problem. [1] <https://github.com/php/php-src/commit/51cdd3dc50af88461d83aec0fac1dca83400b58f>