I am about to show you a great sql trick that only a few SQL Server T-SQL masters actually know. It will save you a decent amount of coding and make you the envy of your Sql Server colleagues.
Even in the Microsoft documentation on the CASE statement does not list that the CASE … WHEN…THEN…END statement can actuall not only check for logical boolean expressions but via operators but it can also handle an IN() statement similar to a fullblown SQL (or SQL Sub-Query statement, if so inclinded) function in the where clause. The code is quite simple. I have not found any restrictions when using constants (the hard-coded text that does not change) or immediate variables that are defined within the execution frame of the CASE IN() statment such as CASE WHEN something IN(@supertest). That is where @supertest = ‘A, B, C’.
Here is an decent example so enjoy and share with your friends. Be sure to comment on this if you like it. We are trying to gain a rep here at ArtOfBi.com!
WHEN ‘C’ THEN
CASE WHEN accountTypeID IN(1, 4, 7) THEN
[amount] * -1
WHEN ‘D’ THEN
CASE WHEN accountTypeID IN(2, 3, 6) THEN
[amount] * -1
CASE dataElement1 IN(‘asset’, ‘liability’) THEN
END AS something
I have not seen any performance issues with the use of this case statement. It works like a charm for me on tables with 10,000+ records. As a side note, using the CASE IN() statement requires only two rigid assumptions:
- The IN statment must be immediately next to the parenthesis (i.e. no space between the two) ex: IN(‘yes’, ‘no’) and not IN (‘yes’, ‘no’)
- The values must be seperated by a comma. If the value is a string it must be contained as a string in single-tick quotes.
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It’s 2015 and you can now establish totally respectable MS SQL DBA credibility just by mentioning you have been in the game since SQL Server version 9. You may even get the same gasps of shock from some colleagues that used to be reserved for the version 6 veterans.