Art of BI: SQL Server CASE IN() Statement Revealed- Who Knew?

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!
[sourcecode language=’sql’]
SELECT
accountID,
accountSubID,
CASE [debitOrCredit]
WHEN ‘C’ THEN
CASE WHEN accountTypeID IN(1, 4, 7) THEN
[amount] * -1
ELSE
[amount]
END
WHEN ‘D’ THEN
CASE WHEN accountTypeID IN(2, 3, 6) THEN
[amount] * -1
ELSE
[amount]
END
ELSE
[amount]
END
AS amount
,
CASE dataElement1 IN(‘asset’, ‘liability’) THEN
‘Budget Account’
ELSE
‘Income Account’
END AS something
FROM
FactDataTable
[/sourcecode]

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:

  1. 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’)
  2. 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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Christian Screen
Christian is an innovator in analytics and data warehousing design, best practices, and delivery. With more than fifteenyears of decision support and data warehousing with key experiences at Office Depot HQ, Sierra-Cedar, and Capgemini, he oversees the Oracle Analytics Practice which includes the technical development and delivery of Oracle BI collaboration software, data warehouse solutions, Oracle BI/EPM projects, and packaged analytics solutions at Datavail.

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5 thoughts on “Art of BI: SQL Server CASE IN() Statement Revealed- Who Knew?”
  1. Nice example… but I knew… This works just like the WHERE…IN clause. A space between the "IN" and the "(" is most definitely allowed. You are correct that strings must be enclosed in single-quotes – standard TSQL syntax…

    DECLARE @x INT
    SET @x = 5

    SELECT CASE WHEN @x IN (3,5,7) THEN 'Yup' ELSE 'Nope' END AS RESULT