case()的用法与decode()基本相同：

语法格式为：

selectename ,caseename

when'KING'then'Hello'

when'FORD'then'Word'

when'MILLER'then'HELLOWORD'

elseename

end name

fromemp

wheredeptno =10

ENAME NAME

---------- ----------

CLARK CLARK

KING Hello

MILLER HELLOWORD