批量更新的sql语句写法

最新推荐文章于 2025-06-27 16:39:00 发布

syqc_love

最新推荐文章于 2025-06-27 16:39:00 发布

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分类专栏：数据库文章标签： sql table join sqlserver oracle db2

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本文介绍了一种高效批量更新数据库表的方法，避免了使用存储过程或循环执行SQL带来的不便。通过SQL语句结合多个表联接操作，实现了一次性完成跨表数据更新。

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--Table1字段:fId,Field1,Field2
--Table2字段:fId,Field21,Field22
UPDATE Table1
SET Field1 = Field21, Field2 = Field22
FROM Table2 t2 WHERE Table1.fId = t2.fId);

批量更新表时，update一个表的列时，需要依赖另外的表，这种依赖可以是where条件子句，也可以要update的field的值依赖另外的表
   通常有两种做法
   1.使用存储过程
   2.在程序代码里逐条循环执行
这里给出一种更高效、简洁的做法，批量更新SQL ，一句SQL就可以替代麻烦的循环过程，有MS SQLServer、Oracle、DB2下的写法
--关键点：t4和t1是同一个table，primary key肯定也是同一个，
--并以它进行关联，这样在 select语句里即可引用到要update的表的fields
----------------------------MS SQLServer --------------------------------------

UPDATE t1
SET Field1 = Field21, Field2 = Field22
FROM Table2 t2
         INNER JOIN Table3 t3
              ON t3.Field31 = t2.Field23
         INNER JOIN Table4 t4
              ON t3.Field32 = t4.Filed41
WHERE ((t2.Field24 >= '')
                  AND t1.fId = t4.fId);
----------------------------Oracle --------------------------------------------

UPDATE Table1 t1
SET (Field1,Field2) = (SELECT Field21, Field22
                       FROM Table2 t2
                            INNER JOIN Table3 t3
                                 ON t3.Field31 = t2.Field23
                            INNER JOIN Table4 t4
                                 ON t3.Field32 = t4.Filed41
                       WHERE ((t2.Field24 >= '')
                                 AND t1.fId = t4.fId))
WHERE EXISTS (SELECT Field21, Field22
              FROM Table2 t2
                   INNER JOIN Table3 t3
                        ON t3.Field31 = t2.Field23
                   INNER JOIN Table4 t4
                        ON t3.Field32 = t4.Filed41
              WHERE ((t2.Field24 >= '')
                               AND t1.fId = t4.fId));
---------------------------------DB2 ------------------------------------------

UPDATE Table1 AS t1
SET (Field1,Field2) = (SELECT Field21, Field22
                       FROM Table2 t2
                            INNER JOIN Table3 t3
                                 ON t3.Field31 = t2.Field23
                            INNER JOIN Table4 t4
                                 ON t3.Field32 = t4.Filed41
                       WHERE ((t2.Field24 >= '')
                                         AND t1.fId = t4.fId))
WHERE EXISTS (SELECT Field21, Field22
              FROM Table2 t2
                   INNER JOIN Table3 t3
                        ON t3.Field31 = t2.Field23
                   INNER JOIN Table4 t4
                        ON t3.Field32 = t4.Filed41
              WHERE ((t2.Field24 >= '')
                                AND t1.fId = t4.fId));