SELECT CASE columnA WHEN '10' THEN 'ten' WHEN '20' THEN 'twenty' END AS myExample SELECT CASE WHEN columnA = '10' THEN 'ten' WHEN columnA = '20' THEN 'twenty' END AS myExample
Case and searched case
In Teiid, to include conditional logic in a scalar expression, you can use the following two forms of the CASE expression:
CASE <expr> ( WHEN <expr> THEN <expr>)+ [ELSE expr] END
CASE ( WHEN <criteria> THEN <expr>)+ [ELSE expr] END
Each form allows for an output based on conditional logic. The first form starts with an initial expression and evaluates WHEN expressions until the values match, and outputs the THEN expression. If no WHEN is matched, the ELSE expression is output. If no WHEN is matched and no ELSE is specified, a null literal value is output. The second form (the searched case expression) searches the WHEN clauses, which specify an arbitrary criteria to evaluate. If any criteria evaluates to true, the THEN expression is evaluated and output. If no WHEN is true, the ELSE is evaluated or NULL is output if none exists.