SQL Server select case when for complex if then else statement

Question

I am writing a select case statement for a complex If Then Else statement where the logic is

If (wp.LINE_OF_BUSINESS = 'A' or wp.LINE_OF_BUSINESS = 'U') and (wr.Relate_Code = 'in') then bf.age
else if (wp.LINE_OF_BUSINESS = 'A' or wp.LINE_OF_BUSINESS = 'U') and (wr.Relate_Code = 'je' or wr.Relate_Code = 'ji') then then bf.age2
else ba.age

how can I write this logic in case when then statement?

Thanks

Answer 1

Try this

 CASE WHEN wp.LINE_OF_BUSINESS IN ( 'A' , 'U')  and wr.Relate_Code = 'in' THEN bf.age
      WHEN wp.LINE_OF_BUSINESS IN ( 'A' , 'U')  and wr.Relate_Code IN ('je', 'ji') THEN bf.age2
      ELSE ba.age
 END

Answer 2

The cleanest and simplest way is to write a UDF

CREATE FUNCTION myAGE(@bType CHAR,  @code CHAR(2), @age1 int, @age2 int) RETURNS Int
AS 
BEGIN
 If (@bType = 'A' or @bType = 'U') and (@code = 'in') then 
    return @age1
else if (@bType = 'A' or @bType = 'U') and (@code = 'je' or @code = 'ji') then 
   return @age2
else 
   return @age1
END

then simply do

SELECT ..., myAge(wp.LINE_OF_BUSINESS, wr.Relate_Code, bf.age, bf.age2),...