ATTRERRMODE

ATTRERRMODE, commonly written as ATTR_ERRMODE in PHP's PDO extension, is an attribute that controls how errors from database operations are reported. It is represented by the constant PDO::ATTR_ERRMODE and can be set on a PDO instance either in the constructor options or later with setAttribute. The value chosen for this attribute determines how PDO surfaces errors to the application.

The available modes are:

- PDO::ERRMODE_SILENT: no error messages or exceptions are raised; error information must be retrieved manually from errorInfo or errorCode.

- PDO::ERRMODE_WARNING: PHP warnings are emitted containing error details.

- PDO::ERRMODE_EXCEPTION: a PDOException is thrown for errors, enabling standard try/catch handling.

ERRMODE_SILENT is the default in many environments, but ERRMODE_EXCEPTION is the most common choice in modern code because it integrates with exception handling and simplifies centralized error management. ERRMODE_WARNING can be useful during development when you want to surface issues without interrupting execution, but it may clutter logs.

Example usage:

- $pdo = new PDO($dsn, $user, $pass, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));

- $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

Compatibility and implications: most PDO drivers support all three modes, though the exact behavior may vary by driver. The error mode does not affect query results themselves, only how errors are surfaced. Choosing an error mode reflects an application's error-handling strategy and debugging workflow, with ERRMODE_EXCEPTION being the predominant recommendation for robust error management.