Control flow in T-SQL SP using IF..ELSE IF - are there other ways?

I need to branch my T-SQL stored procedure (MS SQL 2008) control flow to a number of directions:

CREATE PROCEDURE [fooBar] @inputParam INT AS BEGIN IF @inputParam = 1 BEGIN ... END ELSE IF @inputParam = 3 BEGIN ... END ELSE IF @inputParam = 3 BEGIN ... END END 

Is there any other ways? For example, in C# I shoud use switch-case block.

6 Answers

IF...ELSE... is pretty much what we've got in T-SQL. There is nothing like structured programming's CASE statement. If you have an extended set of ...ELSE IF...s to deal with, be sure to include BEGIN...END for each block to keep things clear, and always remember, consistent indentation is your friend!

Also you can try to formulate your answer in the form of a SELECT CASE Statement. You can then later create simple if then's that use your results if needed as you have narrowed down the possibilities.

SELECT @Result = CASE @inputParam WHEN 1 THEN 1 WHEN 2 THEN 2 WHEN 3 THEN 1 ELSE 4 END IF @Result = 1 BEGIN ... END IF @Result = 2 BEGIN .... END IF @Result = 4 BEGIN //Error handling code END 

No, but you should be careful when using IF...ELSE...END IF in stored procs. If your code blocks are radically different, you may suffer from poor performance because the procedure plan will need to be re-cached each time. If it's a high-performance system, you may want to compile separate stored procs for each code block, and have your application decide which proc to call at the appropriate time.

The Transact-SQL control-of-flow language keywords are:

BEGIN...END
BREAK
CONTINUE
GOTO label
IF...ELSE
RETURN
THROW
TRY...CATCH
WAITFOR
WHILE

Nope IF is the way to go, what is the problem you have with using it?

BTW your example won't ever get to the third block of code as it and the second block are exactly alike.

CASE expression WHEN value1 THEN result1 WHEN value2 THEN result2 ... WHEN valueN THEN resultN [ ELSE elseResult ] END 

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