Case Statement in 'IN' clause in SQL

Question

I am trying to write a case statement inside the IN clause.

The Channel column contains three values ACT, REN, REP. I want to select more than 1 values, but I get result with only one value.

    select * from tbl
    WHERE tbl.Channel IN (select 
                                    case when @ACT =1 then 'ACT'
                                    when @REN =1 then 'REN' 
                                    when @REP =1 then 'REP' END)

What changes should I be doing here ?

Answer 1

Don't end your case. You are returning 3 columns. You only want one.

select * from tbl
    WHERE tbl.Channel =  case when @ACT =1 then 'ACT' 
                              when @REN =1 then 'REN'
                              when @REP =1 then 'REP' 
                              else NULL END

Answer 2

This will work fine. SQL Fiddle

The only change is removing the select so the input to the in clause is 3 values rather than a single row with three columns.

The implicit else null if the variable is not 1 does not cause a problem in an in clause.

SELECT * 
FROM   tbl 
WHERE  tbl.channel IN ( CASE 
                          WHEN @ACT = 1 THEN 'ACT' 
                        END, CASE 
                          WHEN @REN = 1 THEN 'REN' 
                        END, CASE 
                               WHEN @REP = 1 THEN 'REP' 
                             END ) 

Answer 3

You can write the clause without a case at all:

select *
from tbl
where (tbl.Channel 'ACT' and @ACT = 1) or
      (tbl.Channel = 'REN' and @REN = 1) or
      (tble.Channel = 'REP' and @REP = 1);

Your select statement is not correct and should return an error. select statements in in clauses are not allowed to return more than one column.

Answer 4

Here is an alternative that should let you perform the selection without an IN operator:

select * from tbl
WHERE (tbl.Channel='ACT' AND @ACT=1)
   OR (tbl.Channel='REN' AND @REN=1)
   OR (tbl.Channel='REP' AND @REP=-1)

If you must use IN operator, you should be able to construct a query with UNION ALL , like this:

select * from tbl
WHERE tbl.Channel IN (
    select case when @ACT =1 then 'ACT' END FROM DUAL
        UNION ALL
    select case when @REN =1 then 'REN' END FROM DUAL
        UNION ALL
    select case when @REP =1 then 'REP' END FROM DUAL)

Demo.