@H_404_1@我创建了两张桌子和一张桌子.插入的值如下所示.

@H_404_1@表格1

@H_404_1@

create table maxID (myID varchar(4));

insert into maxID values ('A001');
insert into maxID values ('A002');
insert into maxID values ('A004');
insert into maxID values ('A003');

@H_404_1@表2

@H_404_1@

create table maxID2 (myID varchar(4) PRIMARY KEY);

insert into maxID2 values ('A001');
insert into maxID2 values ('A002');
insert into maxID2 values ('A004');
insert into maxID2 values ('A003');

@H_404_1@当我执行查询

@H_404_1@

SELECT myId,@rowid:=@rowid+1 as myrow 
FROM maxID,(SELECT @rowid:=0) as init
ORDER BY myrow desc
LIMIT 1;

@H_404_1@我输出为

@H_404_1@

+++++++++++++
myid + myrow
+++++++++++++
A003 + 4
+++++++++++++

@H_404_1@和

@H_404_1@当我执行查询

@H_404_1@

SELECT myId,@rowid:=@rowid+1 as myrow 
FROM maxID2,(SELECT @rowid:=0) as init
ORDER BY myrow desc
LIMIT 1;

@H_404_1@我输出为

@H_404_1@

+++++++++++++
myid + myrow
+++++++++++++
A004 + 4
+++++++++++++

@H_404_1@两个表之间的区别在于,在第二个表中,我将myID作为PRIMARY KEY.

@H_404_1@您可以在www.sqlfiddle.com查看上述数据/结果.

@H_404_1@我的问题是

@H_404_1@为什么在查询相同时我得到两个不同的结果？

@H_404_1@注意：这个问题与我的旧问题Getting last record from mysql有点相关,我几乎得到了答案,Yak通知我,行的顺序无法保证.