mysql多表join时候update更新数据的方法
人气:0如果item表的name字段为''就用resource_library 表的resource_name字段前面加上字符串Review更新它,他们的关联关系在表resource_review_link中。
sql语句：复制代码 代码如下:
update item i,resource_library r,resource_review_link l set i.name=CONCAT('Review:',r.resource_name) where i.item_id=l.instance_id
and l.level='item' and r.resource_id=l.resource_id and i.name=''
JOIN UPDATE & JOIN DELETE
复制代码 代码如下:
update a
set a.schoolname = b.schoolname
from tb_Std as a join tb_Sch as b on a.School = b.School
where a.std_year = 2005
go
/*
(2 row(s) affected)
*/
select *
from tb_Std as a join tb_Sch as b on a.School = b.School
/*
A School A A School
2 2005 A A School A A School
3 2004 C A School C C School
4 2005 D D School D D School
(4 row(s) affected)
*/
复制代码 代码如下:
delete a
from table1 a, table2 b
where a.col1 = b.col1
and a.col2 = b.col2
The above SQL statement runs fine in SQL Server.
If the Oracle 9i has different syntax or if there is any other way to accomplish this with a single delete statement that would be really helpful.
> Hi,
>
> Is the following delete statement possible in Oracle 9i.
>
> delete a
> from table1 a, table2 b
> where a.col1 = b.col1
> and a.col2 = b.col2
>
> The above SQL statement runs fine in SQL Server.
>
> If the Oracle 9i has different syntax or if there is any other way to accomplish this with a single delete statement that would be really helpful.
>
> Thanx in advance.
>
> -Bheem
Bheem,
Try this:
DELETE FROM table1 a where exists (select 1 from table2 b
where a.col1 = b.col1 and a.col2 = b.col2);
Hope this helps,
Tom K.
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