sql中常用的语句

1 多个字段更新

UPDATE a

SET    a = b.a,

       b = b.b,

       c = b.c

FROM   t a,

       t b

WHERE  (a.条件1)

       AND (b.条件2)




2 update table1 t set t.safety_dep=(select uuid from safety_unit where safety_office='45') 

where t.safety_dep='1';  

3  oracle数据库中改变表中字段的类型

alter table table1    rename column device_number to device_number_temp;
alter table table1 add device_number varchar2(32);
update table1 set device_number=device_number_temp;
alter table table1   drop column device_number_temp;
commit;

4 update assist_team t set 
  t.corp_uuid=(select c.safety_office from safety_unit c where c.full_name=t.corp_name)
 ,t.member_uuid=(select c.safety_office from safety_unit c where c.full_name=t.corp_name)
  where exists (select 1 from safety_unit a where a.full_name=t.corp_name);

update assist_team t set t.corp_uuid=45,t.dept_uuid=45 where corp_uuid='1';