假设id是唯一的,可以这样写SQL语句:
select * from tblName where id in(select max(id) from tblName a,
(select `name`,max(`date`) as maxDate
from tblName group by `name`) b
where a.`name`=b.`name` and a.`date`=b.maxDate
group by a.`name`) order by id
call sp_add()像我这样是可以的:
CREATE PROCEDURE sp_add(a int, b int,out c int)
begin
set c=a+ b
end
调用过程:
call sp_add (1,2,@a)
select @a
本文主要展示如何使用mysql的多列组合查询
多列组合查询平常比较少见,初次看还觉得挺神奇的。
• mysql-filtering-by-multiple-columns[1]
• selecting-where-two-columns-are-in-a-set[2]
[1] mysql-filtering-by-multiple-columns https://www.tutorialspoint.com/mysql-filtering-by-multiple-columns
[2] selecting-where-two-columns-are-in-a-set https://dba.stackexchange.com/questions/34266/selecting-where-two-columns-are-in-a-set
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