ThesqlCASEexpression is a generic conditional expression,similar to if/else statements in other programming languages:
- CASE WHEN condition THEN result
- [WHEN ...]
- [ELSE result]
- END
An example:
- SELECT * FROM test;
- a
- ---
- 1
- 2
- 3
- SELECT a,CASE WHEN a=1 THEN 'one'
- WHEN a=2 THEN 'two'
- ELSE 'other'
- END
- FROM test;
- a | case
- ---+-------
- 1 | one
- 2 | two
- 3 | other
http://www.postgresql.org/docs/current/static/functions-conditional.html