mysql - sql中insert语句中的select语句返回多行

Question

我在 mysql 中有以下结构化查询。但它返回一个错误。基本上，我想从现有表中获取值(value)并插入到新表中。我尝试了以下操作，但出现错误；

INSERT INTO `table1`(
    `first`,`second`,`third`) VALUES(

    (SELECT table2.timemodified FROM `xtable` AS table2,`ytable` AS table3 
        WHERE table3.id = table2.contextid),

    (SELECT table4.id FROM `ztable` AS table4,`ytable` AS table3 WHERE table4.id = table3.instanceid),

    (SELECT murs.id FROM `table5` AS murs,
    `xtable` AS table2, 
    `wtable` AS table6, 
    `ytable` AS table3, 
    `vtable` AS table7 
    WHERE murs.id = table2.userid AND table6.id = table2.roleid AND table3.id = table2.contextid AND table7.instance = table3.instanceid AND table6.id =3)
);

我测试过，但错误是:#1242 - 子查询返回多于 1 行。问题是我从 insert 中的 select 查询中获得了不止一条记录。我怎样才能消除这样的错误。

Answer 1

整个查询如下所示。将 * 替换为您要选择的列名!

INSERT INTO table1(first,second,third)

-- replace * with columns name first,second,third
select * from (
-- START YOU'RE select query
(SELECT table2.timemodified FROM `xtable` AS table2,`ytable` AS table3 
        WHERE table3.id = table2.contextid),

    (SELECT table4.id FROM `ztable` AS table4,`ytable` AS table3 WHERE table4.id = table3.instanceid),

    (SELECT murs.id FROM `table5` AS murs,
    `xtable` AS table2, 
    `wtable` AS table6, 
    `ytable` AS table3, 
    `vtable` AS table7 
    WHERE murs.id = table2.userid AND table6.id = table2.roleid AND table3.id = table2.contextid AND table7.instance = table3.instanceid AND table6.id =3)
-- END YOU'RE select query
)

我将您的选择语句移到了子查询中，这样您就可以使用子查询的总结果来获得优势。