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  • mysql 各种级联查询后更新(update select).

    mysql  各种级联查询后更新(update select).

    CREATE TABLE `tb1` (
      `id` int(11) NOT NULL,
      `A` varchar(100) default NULL,
      `B` varchar(100) default NULL,
      `C` varchar(20) default NULL,
      PRIMARY KEY  (`id`),
      KEY `id` (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

    CREATE TABLE `tb2` (
      `id` int(11) NOT NULL,
      `A` varchar(100) default NULL,
      `B` varchar(100) default NULL,
      PRIMARY KEY  (`id`),
      KEY `id` (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=latin1;


    级联更新1:

    update tb1,
    tb2
    set tb1.a=tb2.a,tb1.b=tb2.b
    where tb1.id=tb2.id

    级联更新2:

    update tb1,
    (select * from tb2) as tb2
    set tb1.a=tb2.a,tb1.b=tb2.b
    where tb1.id=tb2.id

    级联更新3:

    update (select * from tb1 group by C) as temp,
           tb2,
           tb1
    set tb1.a = tb2.a,
        tb1.b = tb2.b
    where tb1.id = tb2.id and
          temp.id = tb2.id

    级联更新4:

    update tb1 left join tb2 on tb1.id = tb2.id
    set tb1.a = tb2.a,
        tb1.b = tb2.b
    where ......

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  • 原文地址:https://www.cnblogs.com/jpfss/p/9007770.html
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