mysql中如何将2张表联立排序？

2张表关联排序,用union来做.

SELECT * FROM (SELECT id,ach,'X' AS counter,'A' AS class,date FROM tablename1 as t1 WHERE 1 UNION SELECT id,ach,counter,'B' AS class,date FROM tablename2 as t2 WHERE 1) AS tall order by date asc

建议增加条件,且为索引字段.其次查的数据量不能太大,不然临时表会占据较多的内存空间.宁可牺牲硬盘空间,也不要无谓的牺牲内存空间.

从长远角度来说,建议整合2个表.

当然可以

可以 先把两个表 用 union all 联接，然后 在外面直接 select * from A_and_B order by createDate

基本语句

select * from (

select exp1,exp2,……expn,createDate from a

union all

select exp1,exp2,……expn,createDate from b

) as a_and_b order by createDate

注意，union all 中的两个 select 中，需要 一样多的 与 相同顺序的 字段

select * from（SELECT count(*) as count FROM `medal` `m` INNER JOIN `medal_list` `ml` ON `ml`.`medalId`=`m`.`Id` GROUP BY ml.stuId

） table_a order by table_a.count desc

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