使用来自另一个表的数据更新一个表中的行,基于每个表中的一列相等

Question

基于每个表中的一个列相等(user_id),将多个行从另一个表更新为一个表.

两个表都有一user_id列.需要从数据插入t2到t1当user_id列相等.

提前感谢您提供的任何帮助.

Answer 1

update 
  table1 t1
set
  (
    t1.column1, 
    t1.column2
      ) = (
    select
      t2.column1, 
      t2.column2
    from
      table2  t2
    where
      t2.column1 = t1.column1
     )
    where exists (
      select 
        null
      from 
        table2 t2
      where 
        t2.column1 = t1.column1
      );

或者这个(如果t2.column1 <=> t1.column1是多对一的,其中任何一个都是好的):

update 
  table1 t1
set
  (
    t1.column1, 
    t1.column2
      ) = (
    select
      t2.column1, 
      t2.column2
    from
      table2  t2
    where
      t2.column1 = t1.column1
    and
      rownum = 1    
     )
    where exists (
      select 
        null
      from 
        table2 t2
      where 
        t2.column1 = t1.column1
      ); 

Answer 2

如果要使用t2中的数据更新t1中的匹配行,则:

update t1
set (c1, c2, c3) = 
(select c1, c2, c3 from t2
 where t2.user_id = t1.user_id)
where exists
(select * from t2
 where t2.user_id = t1.user_id)

"where exists"部分用于防止在不存在匹配的情况下将t1列更新为null.

Answer 3

merge into t2 t2 
using (select * from t1) t1
on (t2.user_id = t1.user_id)
when matched then update
set
   t2.c1 = t1.c1
,  t2.c2 = t1.c2

Answer 4

如果记录已存在于t1(user_id匹配)中,则它不是插入,除非您乐意创建重复的user_id.

您可能想要更新？

UPDATE t1
   SET <t1.col_list> = (SELECT <t2.col_list>
                          FROM t2
                         WHERE t2.user_id = t1.user_id)
 WHERE EXISTS
      (SELECT 1
         FROM t2
        WHERE t1.user_id = t2.user_id);

希望能帮助到你...