How Can I Debug \'Query Failed\' Errors in PHP When Using Dynamic MySQL Queries?

How to Handle MySQL Errors in PHP Long Queries with Dynamic User Input

When executing complex MySQL queries in PHP that rely on user input, it's crucial to handle errors effectively to identify and resolve issues. In this case, you encountered a generic "Query Failed" message that provides little insight into the cause of the failure.

To address this, you can leverage built-in PHP functions to retrieve detailed error messages. Here's an enhanced version of your code:

<?php
//... Your other code

$r = mysqli_query($this->db_link, $query) or die(mysqli_error($this->db_link));

if ($r == false)
    printf("error: %s\n", mysqli_errno($this->db_link));
?>

The or die(mysqli_error($this->db_link)) command will halt script execution and print the error message if the query fails. Alternatively, you can use mysqli_errno() to obtain just the error code for further processing. Refer to the PHP documentation for additional details on these functions.

By incorporating these techniques, you can effectively diagnose and resolve MySQL errors, ensuring the smooth execution of your dynamic queries and the clarity of error reporting when problems arise.

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