Expresia CASE

Permite o logica de tipul IF-THEN-ELSE în fraze SQL  fara  necesitatea de a invoca proceduri. Forma generala este:
 
CASE expr WHEN expr_comp1 THEN   expr1
                [WHEN expr_comp2   THEN expr2
                WHEN expr_compn  THEN  exprn
ELSE expr_alternativa]
END
 
Exemple:
SELECT marca, nume, colaborator,
    CASE colaborator
        WHEN ‘N’ THEN ‘Angajat permanent’
        WHEN ‘D’ THEN ‘Colaborator’
    ELSE ‘Nu este specificat!’
    END AS Tip_angajat
FROM personal
Sau
SELECT marca, nume, colaborator,
    CASE
        WHEN colaborator =‘N’ THEN ‘Angajat permanent’
        WHEN colaborator = ‘D’ THEN ‘Colaborator’
    ELSE ‘Nu este specificat!’
    END AS Tip_angajat
FROM personal