由一个表更新另一个表中field

来源:http://hi.baidu.com/chaowei_yuwen/blog/item/e2078ecbabccc081c9176841.html

由一个表里的数据更新另一个表里的数据：
情况：
因为操作错误，导致库存里件号和货品不符合，用新提供的excel数据(很多，而且仅仅批号lot_no和货品prod_id)去更新原有数据。
做法：
建立临时表(用临时表导数据是一种技巧)
SQL：
update inventory set prod_id=
(
select prod_id from inventory_temp where inventory_temp.lot_no=inventory.lot_no
)
where exists
(
select lot_no from inventory_temp where inventory_temp.lot_no=inventory.lot_no
)
体会：
用一个表去更新另一个表
上边写法可以简写为：
update a
set a.name=(select b.name from a.id = b.id)
where exsits (select 1 from a.id = b.id);
如果更新的是多个字段：
UPDATE employees a
    SET department_id =
        (SELECT department_id
            FROM departments
            WHERE location_id = '2100'),
        (salary, commission_pct) =
        (SELECT 1.1*AVG(salary), 1.5*AVG(commission_pct)
          FROM employees b
          WHERE a.department_id = b.department_id)
    WHERE department_id IN
        (SELECT department_id
          FROM departments
          WHERE location_id = 2900
              OR location_id = 2700);

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

另外一个: http://blog.csdn.net/Bobwu/archive/2009/01/13/3768636.aspx

declare
cursor t1 is select * from tablename;
begin
for rec in t1 loop
update tablename t set t.detail=rec.jieshao where t.objectid=rec.objid;
end loop;
end;

update   student   set   (name,id   )=
(select   name   ,id     from   (select   student.rowid   rd,student1.name,student1.id   from   student1,student   where   student1.int_id   =student.int_id)   tmp
where   student.rowid=tmp.rd);
commit;

update test_a a set (a.name,a.age)=
(select b.name,b.age from test_b b where a.id = b.id) where exists
(select * from test_b c where c.id=a.id)

UPDATE   t_A   SET   Djrq=
(
          SELECT   djrq   FROM   t_B   WHERE   t_A.ID   =   T_B.ID
          WHERE   ROWNUM   =   1
)
WHERE   t_A.ID   IN
(
          SELECT   ID   FROM   t_B   WHERE   jwh='XX村'
)

update tbl1 a
   set (a.col1, a.col2) = (select b.col1, b.col2
                              from tbl2 b
                              where a.key = b.key)
   where a.key in(select key from tbl2)