求批量更新MySQL语句

[伏伏]

有表 post,里面有两个字段pid,subject
有9万条数据，按pid排序
现在我要把
第1条的subject=第30000条的subject
第2条的subject=第30001条的subject
...
第29999条的subject=第59999条的subject

这个SQL语句该怎么写呀？

[伏伏]

在线等啊等啊。

[zuoxingyu]

update post A ,post B set A.subject=B.subject where a.pid+29999=b.pid

[伏伏]

[Quote=引用 2 楼 zuoxingyu 的回复:]
update post A ,post B set A.subject=B.subject where a.pid+29999=b.pid
[/Quote]
这个貌似不对，因为pid不是连续的。

[ACMAIN_CHM]

9万条数据，如果用SQL语句实现，速度太慢了。建议用程序或者用存储过程来实现吧。
除非你的PID是连续的从1 开始正好与顺序相等（中间没有断号），则可以用简单的SQL语句实现

update post a inner jion post b on a.pid=b.pid-30000+1 set a.subject=b.subject where a.pid <30000

[伏伏]

[Quote=引用 4 楼 acmain_chm 的回复:]
9万条数据，如果用SQL语句实现，速度太慢了。建议用程序或者用存储过程来实现吧。
除非你的PID是连续的从1 开始正好与顺序相等（中间没有断号），则可以用简单的SQL语句实现

update post a inner jion post b on a.pid=b.pid-30000+1 set a.subject=b.subject where a.pid <30000
[/Quote]
程序或者存储过程怎么写呀？

谢谢了。
有现成的代码最好了。谢谢。

[伏伏]

谁能帮助写一个呀。PID不是连续的。

[伏伏]

[Quote=引用 4 楼 acmain_chm 的回复:]
9万条数据，如果用SQL语句实现，速度太慢了。建议用程序或者用存储过程来实现吧。
除非你的PID是连续的从1 开始正好与顺序相等（中间没有断号），则可以用简单的SQL语句实现

update post a inner jion post b on a.pid=b.pid-30000+1 set a.subject=b.subject where a.pid <30000
[/Quote]
acmain_chm大哥，帮助写个吧？谢谢啦！

[zuoxingyu]

提供个思路吧；
1：create table tmp1 (id int,pid int,subject varchar(200));
2: create table tmp2 (id int,pid int,subject varchar(200));
3:
declare @ID int;
set @ID:=0;
select @ID:=@ID+1 as ID,pid,subject in tmp1 from tmpcard limit 29999;

4:
declare @ID int;
set @ID:=30000;
select @ID:=@ID+1 as ID,pid,subject in tmp2 from tmpcard limit 30000,29999;

5:update tmp1 A ,tmp2 B set A.subject=B.subject where a.pid+29999=b.pid

6:delete from post,tmp1 where post.pid=tmp.pid;
7:insert into post values select pid,subject from tmp1;

8:drop table tmp1,tmp2;

[zuoxingyu]

以为你的pid不连续，那么人为制造一个连续的ID

再根据这个ID去去30000条，再进行修改。

代码不对的地方自己修正一下。

[伏伏]

那如果表中不止这两个字段就在下面的代码里面自己加是吧？

[Quote=引用 8 楼 zuoxingyu 的回复:]
提供个思路吧；
1：create table tmp1 (id int,pid int,subject varchar(200));
2: create table tmp2 (id int,pid int,subject varchar(200));
3:
declare @ID int;
set @ID:=0;
select @ID:=@ID+1 as ID,pid,subjec……
[/Quote]

[zuoxingyu]

是的。

人工做一个按顺序排列的字段出来。这是主要思路。

[伏伏]

create table tmp1 (id int,pid int,subject varchar(200));
create table tmp2 (id int,pid int,subject varchar(200));
declare @ID int;
set @ID:=0;
select @ID:=@ID+1 as ID,pid,subject in tmp1 from pra_forum_post limit 23999;
declare @ID int;
set @ID:=30000;
select @ID:=@ID+1 as ID,pid,subject in tmp2 from pra_forum_post limit 24000,23999;
update tmp1 A ,tmp2 B set A.subject=B.subject where a.id+29999=b.id
update pra_forum_post,tmp1 set pra_forum_post.subject=tmp1.subject where pra_forum_post.pid=tmp1.pid;
drop table tmp1,tmp2;

[伏伏]

谢谢你zuoxingyu。thank you very much！！！

[伏伏]

create table tmp1 (id int,pid int,subject varchar(200));
create table tmp2 (id int,pid int,subject varchar(200));
declare @ID int;
set @ID:=0;
select @ID:=@ID+1 as ID,pid,subject in tmp1 from pra_forum_post limit 23999;
declare @ID int;
set @ID:=24000;
select @ID:=@ID+1 as ID,pid,subject in tmp2 from pra_forum_post limit 24000,23999;
update tmp1 A ,tmp2 B set A.subject=B.subject where a.id+23999=b.id
update pra_forum_post,tmp1 set pra_forum_post.subject=tmp1.subject where pra_forum_post.pid=tmp1.pid;
drop table tmp1,tmp2;

[ACMAIN_CHM]

mysql> select * from post;
+-----+---------+
| pid | subject |
+-----+---------+
|   1 | A01     |
|   3 | A02     |
|  31 | A16     |
|  33 | A17     |
|   9 | A05     |
|  11 | A06     |
|  13 | A07     |
|  15 | A08     |
|   7 | A04     |
|  19 | A10     |
|  21 | A11     |
|  23 | A12     |
|  39 | A20     |
|  41 | A21     |
|  25 | A13     |
|  27 | A14     |
|  29 | A15     |
|  35 | A18     |
|  17 | A09     |
|   5 | A03     |
|  37 | A19     |
|  43 | A22     |
|  45 | A23     |
|  47 | A24     |
+-----+---------+
24 rows in set (0.00 sec)

mysql> delimiter ;
mysql> delimiter //
mysql> create procedure x()
    -> begin
    ->  DECLARE done INT DEFAULT 0;
    ->  DECLARE a,b INT;
    ->  DECLARE c varchar(10);
    ->  DECLARE cur1 CURSOR FOR SELECT pid FROM post order by pid limit 10;
    ->  DECLARE cur2 CURSOR FOR SELECT pid,subject FROM post order by pid limit
10,10;
    ->  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
    ->
    ->  OPEN cur1;
    ->  OPEN cur2;
    ->
    ->  FETCH cur1 INTO a;
    ->  FETCH cur2 INTO b, c;
    ->
    ->  WHILE done = 0 DO
    ->          update post set subject=c where pid=a;
    ->
    ->          FETCH cur1 INTO a;
    ->          FETCH cur2 INTO b, c;
    ->   END WHILE;
    ->  CLOSE cur1;
    ->  CLOSE cur2;
    ->
    -> end;//
Query OK, 0 rows affected (0.09 sec)

mysql> delimiter ;
mysql> call x();
Query OK, 1 row affected (0.05 sec)

mysql> select * from post order by
+-----+---------+
| pid | subject |
+-----+---------+
|   1 | A11     |
|   3 | A12     |
|   5 | A13     |
|   7 | A14     |
|   9 | A15     |
|  11 | A16     |
|  13 | A17     |
|  15 | A18     |
|  17 | A19     |
|  19 | A20     |
|  21 | A11     |
|  23 | A12     |
|  25 | A13     |
|  27 | A14     |
|  29 | A15     |
|  31 | A16     |
|  33 | A17     |
|  35 | A18     |
|  37 | A19     |
|  39 | A20     |
|  41 | A21     |
|  43 | A22     |
|  45 | A23     |
|  47 | A24     |
+-----+---------+
24 rows in set (0.00 sec)

mysql>

[wwwwb]

zuoxingyu的方法不错