I am developing a wordpress site and I would like to be able to log and handle mysql errors from wordpress core.

My site has a mix of wordpress pages and posts + a few php pages that run under the wordpress engine. I configured the php.ini to prepend a php file to all php scripts with the error handling functions. They are working fine to catch php errors both in the wordpress core and in my own php scripts.

I also catch all the MySQL errors in my own php scripts. For example, failure to connect to a database, etc.

I would like to be able to also catch, log and process eventual MySQL errors from the wordpress core application.

Any suggestions?


I was reading through the codex and I couldn't find an answer

  • What are you doing that cannot be done with $wpdb or WP_Query?
    – Tom J Nowell
    Jun 13 '15 at 2:28

You should be using the wpdb class for all your own queries. All core queries also use wpdb. See wpdb Show and Hide SQL Errors

<?php $wpdb->show_errors(); ?> 
<?php $wpdb->hide_errors(); ?> 

You can also print the error (if any) generated by the most recent query with print_error.

<?php $wpdb->print_error(); ?>

Also see SAVEQUERIES constant for wp-config.php:

define('SAVEQUERIES', true);

usage example:

if (current_user_can('administrator')){
    global $wpdb;
    echo "<pre>";
    echo "</pre>";

There are also a number of helpful debugging plugins, like Debug Bar & Console. Search the WordPress plugin repository for this and other debugging related plugins.


One way to do this:

  1. Create a file called db.php in wp-content. Wordpress will read this file immediately before instantiating the $wpdb object.
  2. Create a class which extends wpdb, and overwrite the print_errors method to do whatever you want.
  3. In the end of that file, instantiate your class, setting it the variable $wpdb (eg., $wpdb = new wpdb2(DB_USER, DB_PASSWORD, DB_NAME, DB_HOST);)
  4. Wordpress will now use your $wpdb instead.

try with

global $wpdb;
echo $wpdb->last_query;

as i am working with ajax, this is directly in string form.

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