How To Write SQL Server Queries Correctly: Subqueries

[@jasonpeak8899]

Love this kind of conversation. I've worked most of my adult life in the ERP space and can probably count on one hand the number of developers I've worked with who don't call it a day when their query returns the data they expected. If you're writing a report that the end user doesn't care if it takes five minutes to complete, that's one thing. If you're putting code into a database insert/update trigger, that's a whole different situation. Started writing SQL in Informix SQL/4GL on AT&T Unix System V, so I appreciate every CPU cycle...you used to know a bad query from the disk thrashing.

[@ErikDarlingData]

Ha ha, that sounds like a fun time. I do sometimes miss those hard drive noises.

I have yet to see an example of subqueries in the select list in the wild that wasn't terrible. So this is one of those things where you can either just tell people not to do it or send them for a few days of training.

[@ErikDarlingData]

I believe that’s what the point of this video is, so send them here.

[@mattcargile]

Subqueries and derived tables can get confused. A lot of times I think folks say subquery when they mean derived tables.

[@ErikDarlingData]

Maybe I’ll start calling CTEs subqueries.

[@anuragkumar-dm1er]

Sorry for asking but is there a way I can get the script used in the video ?

[@ErikDarlingData]

I only provide scripts with paid training.