Using APPLY To Aggregate Unpivoted Data

Dan Clemens gives us yet another practical use of the APPLY operator:

I had a situation last week where I needed to find the MIN() and MAX() values of some data. Normally this would be pretty straightforward, but the problem was I needed to identify the MIN() and MAX() values amongst multiple columns. So today I bring you a SQL tip using APPLY.

Looking at sys.procedures we can see I have a create_date and a modify_date column for each record. What if we needed to return the MIN() or MAX() value from those 2 (or more) columns?

SELECT [Name]
,create_date
,modify_date
FROM sys.procedures AS p
WHERE p.[name] = 'ChangePassword';

In this two-column example, it’s not too difficult.  As you add more and more columns, the solution remains the same, though the urge to ask why all of these dates are unpivoted might increase…

Related Posts

Locking Azure Resources

Stuart Moore shows us how we can lock Azure resources to prevent accidental mistakes: A resource deletion may not sound like too much of a big thing if you’re deploying Infrastructure as code, hey we’ll just terraform apply again and it’ll pop backup. In theory that’s a great idea, just with one big problem. The new resource […]

Read More

Automate VM Shutdown

Meagan Longoria has a script to shut off an Azure VM when a SQL Agent job finishes: The runbook sets the Azure context to the appropriate subscription (especially important when you are a guest user in someone else’s tenant). Then it checks if the VM is started. If it is, it goes into a do-while […]

Read More

Categories

July 2018
MTWTFSS
« Jun Aug »
 1
2345678
9101112131415
16171819202122
23242526272829
3031