[php] How do I display a MySQL error in PHP for a long query that depends on the user input?

Use below code to print the error code :

echo mysqli_errno($this->db_link);

Error code will give you better idea about the error.

More info can be found at https://www.techqura.com/techqura.php?post=How-to-display-MySQL-error-in-PHP&pid=8&website=techqura.com