Example: Using a CASE Expression - Analytics Database - Teradata Vantage

CASE expressions can be used in place of any value-expressions.

Note that the following example does not specify an ELSE clause. ELSE clauses are always optional in a CASE expression. If an ELSE clause is not specified and none of the WHEN conditions are TRUE, then a null is returned.

   SELECT * 
   FROM t 
   WHERE x = CASE 
              WHEN y=2 
              THEN 1
              WHEN (z=3 AND y=5) 
              THEN 2 
             END;