Using an IF statement in a WHERE clause

Question

I have a user defined function and I want to do a select and choose a column based on whether or not it is bigger or small than another.

For example:

Select
   t.A, t.B
From
  Table t
Where
  if(t.A <= t.B) then
    use t.A
  else
    use t.B

Is this possible? Thanks in advance!

Answer 1

It seems like you want

SELECT 
  CASE
    WHEN t.A <= t.B
    THEN t.A 
    ELSE t.B 
  END  AS Smaller
FROM Table t

Answer 2

No! But you can use a case statement

Select
   t.A, t.B
From
   Table t
Where
   (case when t.A <= t.B then t.A ELSE t.B END) = SomeValue

or if the smaller column is required in the select statement only then

Select
   (case when t.A <= t.B then t.A ELSE t.B END) as column
From
   Table t

NOTE I haven't used pervasive sql before, but a quick googlez reveals that the case statement was added in version 9.x??

Answer 3

Do you actually want?

SELECT MIN(t.A, t.B) AS SmallestAOrB FROM Table t