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4GuysFromRolla.com : ASP FAQS : Databases, Queries


How do I use CASE in Transact SQL?

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Answer: Case Statements in Transact SQL
Selection criteria in your Stored Procedures will need to change at times if you really want high reuse out of your Stored Procs. You can use CASE to do this. CASE is very similar to SELECT CASE in any othr data processing language.

The following stored procedure will select a different Price from the database based on the login level of the user.

@cat int,
@Price nvarchar(10)

Select CODE,TITLE,Version,Status,
Case @Price
    When 'Price' THEN Price
    When 'PriceA' Then PriceA
    When 'PriceB' Then PriceB
    When 'PriceC' Then PriceC
From Products
Where Category = @cat ORDER BY CODE

Based on what you have just seen you may be thinking CASE will work everywhere. It would be only practical to assume this will work with the ORDER BY clause.

@cat int,
@Price nvarchar(10)

Select CODE,TITLE,Version,Status,Lots,LotsOf,Description,Pic
From Products Where Category = @cat ORDER BY

Case @Price
    When 'Price' THEN Title
    When 'PriceA' Then Version
    When 'PriceB' Then Status
    When 'PriceC' Then Lots

Well guess what? It will compile file. The syntax checker in SQL Server will not throw an error but IT DOES NOT WORK. SQL server is very fussy about where CASE is used. And in most cases unlogically.

UPDATE (Feb. 6th, 2002)
The above comments are in regard to Microsoft SQL Server 6.5. The above code works in Microsoft SQL Server 7.0 and Microsoft SQL Server 2000.

Visit SQLteam.com for more great information on Transact SQL!

FAQ posted by Rob Taylor at 12/9/2000 4:18:33 AM to the Databases, Queries category. This FAQ has been viewed 75,026 times.

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Last computed at 9/17/2007 3:22:00 AM

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