SQL Language Extension: CASE Function: Allow the result of a column to be determined by a the results of a case expression. Author: Arno Brinkman <firebird@abvisie.nl> Format: <case expression> ::= <case abbreviation> | <case specification> <case abbreviation> ::= NULLIF <left paren> <value expression> <comma> <value expression> <right paren> | COALESCE <left paren> <value expression> { <comma> <value expression> }... <right paren> <case specification> ::= <simple case> | <searched case> <simple case> ::= CASE <value expression> <simple when clause>... [ <else clause> ] END <searched case> ::= CASE <searched when clause>... [ <else clause> ] END <simple when clause> ::= WHEN <when operand> THEN <result> <searched when clause> ::= WHEN <search condition> THEN <result> <when operand> ::= <value expression> <else clause> ::= ELSE <result> <result> ::= <result expression> | NULL <result expression> ::= <value expression> Notes: See also README.data_type_results_of_aggregations.txt Examples: A) (simple) SELECT o.ID, o.Description, CASE o.Status WHEN 1 THEN 'confirmed' WHEN 2 THEN 'in production' WHEN 3 THEN 'ready' WHEN 4 THEN 'shipped' ELSE 'unknown status ''' || o.Status || '''' END FROM Orders o B) (searched) SELECT o.ID, o.Description, CASE WHEN (o.Status IS NULL) THEN 'new' WHEN (o.Status = 1) THEN 'confirmed' WHEN (o.Status = 3) THEN 'in production' WHEN (o.Status = 4) THEN 'ready' WHEN (o.Status = 5) THEN 'shipped' ELSE 'unknown status ''' || o.Status || '''' END FROM Orders o