Window Functions In WHERE Clauses

Kevin Feasel

2018-04-20

Syntax

Shane O’Neill covers an annoying but necessary thing to remember around window functions:

Now, a new learner of SQL comes along with the requirement to find the last 2 rows per PartitionId.

They are diligent and enthusiastic and have just read about Windows Functions. They think to themselves

Wow! This is great! I can do this with Windows Functions!

They also work for a company that has invested in RedGate’s SQL Prompt so they know that they can rely on SQL Prompt to help iron out any inconsistencies in their script.

So they take the SELECT script above and type in WHERE… and the auto complete pops up

And that popup isn’t quite accurate…  Shane covers this in the guise of a SQL Prompt bug, but it’s a good thing to remember regardless of which tooling you use.

Related Posts

Pitfalls with Window Functions

Itzik Ben-Gan takes us through two issues you might run into when using window functions: There are two common pitfalls involving window functions, both of which are the result of counterintuitive implicit defaults that are imposed by the SQL standard. One pitfall has to do with calculations of running totals where you get a window […]

Read More

The If Statement and Friends in Powershell

Kevin Marquette explains what is possible with if in Powershell: The -not operator flips an expression from $false to $true or from $true to $false. Here is an example where we want to perform an action when Test-Path is $false. if ( -not ( Test-Path -Path $path ) ) There’s plenty of good stuff here, so check it out.

Read More

Categories

April 2018
MTWTFSS
« Mar May »
 1
2345678
9101112131415
16171819202122
23242526272829
30