Why Do MySQLi Queries Sometimes Fail Silently, Requiring Explicit False Return Value Checks?

Handling MySQLi Query Errors as Exceptions

Introduction

In MySQLi, query errors are typically reported as warnings or error messages. However, developers may prefer to convert these errors into exceptions for better error handling. This article examines the process of turning MySQLi query errors into exceptions and addresses a common issue where query failures return false without triggering warnings or exceptions.

Problem

When executing MySQLi queries, developers often check if mysqli_query() returned false to detect query errors. However, this approach can be inconvenient, and it may not always catch unexpected errors.

Former Code

$result = mysqli_query($DBlink, $SQL);
if ($result === false) {
    throw new MySQLiQueryException($SQL, mysqli_error($DBlink), mysqli_errno($DBlink));
}

Question

Why is it that in some cases, neither warnings nor exceptions are thrown when a query fails, forcing developers to explicitly check for false return values from mysqli_query()?

Answer

To enable exceptions for MySQLi query errors, you must correctly set the error reporting level using the mysqli_report() function. The following code snippet demonstrates the proper usage:

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

By setting the error reporting level to MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT, MySQLi will start throwing exceptions for all errors and strict errors, including query failures.

Caution

While using exceptions for error handling is generally recommended, it is important to avoid excessive use of try-catch blocks. Error handling should be centralized through a common error handler to minimize code bloat and ensure consistent error reporting.

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