The Art Of The SQL Server Stored Procedure: Debugging


Debugging, like error handling, is a design choice that is fairly easy to make at the outset of writing a stored procedure, and is usually a lot easier to get in there if you do it from the get-go.

The number of times I’ve had to go back and add debugging into something only to introduce debugging bugs is actually a bit tragic.

One of the first things I added debugging to is sp_Blitz, because sometimes queries would fail, and we’d have no idea which one was failing.

Sure, there would be an error message, and a line number, but that all goes pear shaped when you’re dealing with dynamic SQL and nested dynamic SQL and whatnot.

My bright idea was to add lines like this to know which check was starting:

IF @Debug IN (1, 2) RAISERROR('Running CheckId [%d].', 0, 1, 185) WITH NOWAIT;

They’ve changed a little over the years, but it took a few tries to get all the substitution numbers right, and to get them in the right place so they didn’t prevent checks from running.

But now if you @Debug, everything is cool. And if a check fails, you can figure out which one and be a top notch open source contributor by reporting (and even fixing) issues.


I blogged fairly recently about how and why you should do this. I even recorded a video about it:

Where I’m making a really pleasant face in the thumbnail, apparently.

You should check those out if you haven’t already.

Thanks for reading!

Going Further

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3 thoughts on “The Art Of The SQL Server Stored Procedure: Debugging

  1. I started in the bad old days of languages with no debugger.


    Writing my own checks conditionally was easy when I wrote from scratch, less so when I’m sorting someone else’s spaghetti. Now I do verbose modes as well as “debug level” for anything I write.

    See? You are appreciated.

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