Question

Is there a way in TSQL to do something like this:

select a,b,c,
case 
  when a=1 then 5
  when a=2 then 6
end as d
from some_table
where d=6

The actual case statement is really complex, so I’m trying to avoid repeating it in the where clause? Are there any tricks to do this?

(I think there’s a trick in MySQL to use “having d=6”).

Answer 1

select
    a, b, c
from (
    select
        a, b, c,
        case 
          when a=1 then 5
          when a=2 then 6
        end as d
    from some_table
) as t
where d=6