Question

I have a query such as:

SELECT *,
(A+B) AS TOTALVALUE
FROM 
(SELECT A,B FROM MYTABLE) AS MYTABLE1

How can I use a case...when with the calculated value? For example, if my calculated value is greater than 1 I want it to be 10, otherwise I want it to return its value. How can i achieve that?

Answer 1

SELECT *
, (A+B) AS TOTAL VALUE
, case when (A + B) > 1 then 10 else (A + B) end as my_calc_col
FROM MYTABLE

You might also want to consider NULLs:

select 
     x.A
   , x.B
   , case when TOTAL_VALUE > 1 then 10 else TOTAL_VALUE end as TOTAL_VALUE2
from
(
   select coalesce(A, 0) + coalesce(B, 0) as TOTAL_VALUE
          , A
          , B
   FROM MYTABLE
) x

EDIT: I’ve also simplified this bit:

FROM 
(SELECT A,B FROM MY TABLE) AS MYTABLE1

as simply:

SELECT A, B, .....
FROM MYTABLE