I need to change returned value, from select statement, based on several conditions. I tried something like that:

,CASE i.DocValue
  WHEN 'F2' AND c.CondCode IN ('ZPR0','ZT10','Z305') THEN c.CondVal
  ELSE 0
END as Value


why it is not working and what is recommended way to do this ? 
There will be next several WHEN conditions.

Thank you

,CASE WHEN i.DocValue ='F2' AND c.CondCode IN ('ZPR0','ZT10','Z305') THEN c.CondVal
  ELSE 0
END as Value


There are two types of CASE statement, SIMPLE and SEARCHED.

You cannot evaluate multiple expressions in a Simple case expression, which is what you were attempting to do.

-- Simple CASE expression: 
CASE input_expression 
     WHEN when_expression THEN result_expression [ ...n ] 
     [ ELSE else_result_expression ] 
END 
-- Searched CASE expression:
CASE
     WHEN Boolean_expression THEN result_expression [ ...n ] 
     [ ELSE else_result_expression ] 
END


Example of Simple CASE:

CASE x
  WHEN 'a' THEN 'b'
  WHEN 'c' THEN 'd'
  ELSE 'z'
END


Example of a Searched CASE:

CASE 
  WHEN x = 1 AND y = 2 THEN 'a'
  WHEN x = 2 AND y = 1 THEN 'b'
  ELSE 'z'
END


Further Reading: http://msdn.microsoft.com/en-us/library/ms181765.aspx
