Originally way to handle warnings and errors in MySQL stored routine was designed as follows:

• 
  
• if warning was generated during stored routine execution which has a handler for such a warning/error, MySQL remembered the handler, ignored the warning and continued execution
  
• after routine is executed MySQL checked if there is a remembered handler and activated if any
  
  

This logic was not ideal and causes several problems, particularly:

• 
  
• it was not possible to choose right handler for an instruction which generated several warnings or errors, because only first one was chosen
  
• handling conditions in current scope messed with conditions in different
  
• there were no generated warning/errors in Diagnostic Area that is against SQL Standard.
  
  
…

It”s not the most common task in the world, but you might want to view processes from a particular user and once in a while you might even need to kill processes from a single user, be it during an attack or because you simply got a bug in an application bombarding your db server with connections!

Here is a small stored procedure which does exactly that!

call process_list("show","username","hostname");

– shows all processes owned by username@hostname

call process_list("kill","username","hostname");

– kills all processes owned by username@hostname

The code for this stored procedure can be found below. If you have any comments / suggestions feel free to comment below.

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