sql - 从 3 个不同的表中更新字段

Question

我有一个使用以下 3 个表格的问题：

1. Company (table)
CONAME
COPOINTS

2. Group_Member (table)
CONAME
NAME

3. Member (table)
NAME
MPOINTS

我想有一个正确的查询，条件如下：

Update Member
Set MPOINTS=MPOINTS+5
Where Company.CONAME=Group_Member.CONAME
And
Group_Member.NAME=Member.NAME

你能更正上面的查询吗？

Answer 1

在 T-SQL（MS-SQL Server 方言）中，这将是

Update Member
   set MPOINTS = MPOINTS + 5
  from Group_Member 
       join Company on Company.CONAME = Group_Member.CONAME
 where Group_Member.NAME = Member.NAME

我想提醒您，名称对于主键和外键关系都不是一个好的选择。如果不违反主键约束，您将永远无法更改名称。请改用（数字、自动增量）ID 列。

Answer 2

尝试这个：

Update M
Set    MPOINTS=MPOINTS+5
from   Member M 
join   Group_Member GM
on     GM.NAME=M.NAME
join   Company C
on     C.CONAME=GM.CONAME

Answer 3

SQL Server 2005+

UPDATE x
SET x.MPOINTS += 5
FROM (SELECT m.MPOINTS FROM Company c JOIN Group_Member g ON c.CONAME = g.CONAME
                                      JOIN Member m ON g.NAME = m.NAME) x