如何在 SQL Server 中使用 JOIN 执行 UPDATE 语句? [英] How can I do an UPDATE statement with JOIN in SQL Server?

问题描述

我需要使用其父"表中的数据更新 SQL Server 中的此表，请参见下文:

I need to update this table in SQL Server with data from its 'parent' table, see below:

表:销售

id (int)
udid (int)
assid (int)

表:ud

id  (int)
assid  (int)

sale.assid 包含更新 ud.assid 的正确值.

sale.assid contains the correct value to update ud.assid.

什么查询会这样做?我正在考虑 join 但不确定是否可行.

What query will do this? I'm thinking of a join but I'm not sure if it's possible.

推荐答案

语法严格取决于您使用的 SQL DBMS.这里有一些方法可以在 ANSI/ISO(又名应该适用于任何 SQL DBMS)、MySQL、SQL Server 和 Oracle 中执行此操作.请注意，我建议的 ANSI/ISO 方法通常比其他两种方法慢得多，但如果您使用的是 MySQL、SQL Server 或 Oracle 以外的 SQL DBMS，那么它可能是唯一的方法(例如如果您的 SQL DBMS 不支持 MERGE):

Syntax strictly depends on which SQL DBMS you're using. Here are some ways to do it in ANSI/ISO (aka should work on any SQL DBMS), MySQL, SQL Server, and Oracle. Be advised that my suggested ANSI/ISO method will typically be much slower than the other two methods, but if you're using a SQL DBMS other than MySQL, SQL Server, or Oracle, then it may be the only way to go (e.g. if your SQL DBMS doesn't support MERGE):

ANSI/ISO:

update ud 
     set assid = (
          select sale.assid 
          from sale 
          where sale.udid = ud.id
     )
 where exists (
      select * 
      from sale 
      where sale.udid = ud.id
 );

MySQL:

update ud u
inner join sale s on
    u.id = s.udid
set u.assid = s.assid

SQL 服务器:

update u
set u.assid = s.assid
from ud u
    inner join sale s on
        u.id = s.udid

PostgreSQL:

PostgreSQL:

update ud
  set assid = s.assid
from sale s 
where ud.id = s.udid;

注意，Postgres 的 FROM 子句中不能重复目标表.

Note that the target table must not be repeated in the FROM clause for Postgres.

甲骨文:

update
    (select
        u.assid as new_assid,
        s.assid as old_assid
    from ud u
        inner join sale s on
            u.id = s.udid) up
set up.new_assid = up.old_assid

SQLite:

update ud 
     set assid = (
          select sale.assid 
          from sale 
          where sale.udid = ud.id
     )
 where RowID in (
      select RowID 
      from ud 
      where sale.udid = ud.id
 );

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