Detecting Insertion Failures Due to Unique Keys with MySQL

It is essential to validate unique values within a database table to maintain data integrity. When attempting to insert a duplicate value into a column with a unique constraint, MySQL will appropriately reject the operation. Our objective is to capture this error and provide a tailored response to the user.

The recommended approach for such error handling in PHP involves utilizing PDO (PHP Data Objects). PDO provides a modernized and object-oriented interface for database interactions.

try {
    // ... PDO query execution goes here
} catch (\PDOException $e) {
    // Check the specific error code
    if ($e->errorInfo[1] == 1062) {
        // Unique key constraint violation handling (e.g., user notification)
    }
}

The PDOException contains detailed information about the error, including the MySQL error code, which can be used to specifically identify the unique key constraint violation. This allows you to handle the error gracefully and provide meaningful feedback to the user, informing them that the value being inserted already exists in the database.