Why Does PDO Insert 1 Instead of 0 into a BIT(1) Column in MySQL?

PDO Statement Insertion Anomaly with Bit(1) Field

When inserting values into a bit(1) field using PDO prepared statements, an unexpected result occurs. Instead of the intended 0 value, the database stores 1 in the table.

This anomaly arises due to the binary nature of BIT columns in MySQL. Despite being categorized as numeric, they are treated as binary types, leading to compatibility issues with certain client libraries.

Solution using TINYINT(1)

To avoid this problem, consider switching to a TINYINT(1) column instead. This alternative data type offers similar storage requirements to BIT(1) while eliminating compatibility issues with PDO and other client libraries.

Using bindValue with PDO::PARAM_INT

If changing the column type is not feasible, an alternative solution involves using bindValue with the PDO::PARAM_INT type hint. This approach forces PDO to treat the value as an integer, resolving the insertion anomaly.

Example Code

<code class="php">$pdo = new PDO("connection string etc");
$statement = $pdo->prepare('INSERT INTO `test` (SomeText,TestBool) VALUES (:someText,:testBool)');
$statement->bindValue(':someText', "TEST");
$statement->bindValue(':testBool', 0, PDO::PARAM_INT);
$statement->execute();</code>

Note that while this workaround may resolve the insertion issue, it is still advisable to transition to TINYINT(1) for enhanced compatibility and potential performance benefits.

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