oracle CASE例子

create table HH(

USER_ID     NUMBER(4),

AGE       NUMBER(4),

USER_NUMBER NUMBER(4))  

insert into hh(USER_ID,AGE )values(1,12);

insert into hh(USER_ID,AGE )values(2,14);

insert into hh(USER_ID,AGE )values(3,16);

insert into hh(USER_ID,AGE )values(4,11);

commit;

select * from hh;

 update HH   set user_number = (select b.user_number                       

                                                              from (select a.user_id,   

                                                                 case                             

                                                                   when a.age = 12 then '6'                             

                                                                   when a.age = 14 then '7'  

                                                                   when a.age = 16 then '8'                             

                                                                                               else  '9'                             

                                                                             end user_number                             

                                                                                          from hh a) b                      

                                                        where b.user_id = hh.user_id)