我要写个存储过程，传入记录数N。
然后查找出按积分排序的前N条记录，然后循环设置记录的排名=i.
请问能给个demo么。
[code="java"]create procedure batchUpdate(in n int)
begin
declare inParam int default n;
declare i int default 1;
declare id int;
declare username varchar(255);
declare integral varchar(255);
declare ranking int;
declare _resultSet cursor for select a.id, a.username,a.integral,a.ranking from user a order by a.integral desc limit inParam;
open _resultSet;
while i <= inParam do
fetch _resultSet into id, username, integral,ranking;
update user a set a.ranking = i where a.id = id;
set i = i +1;
end while;
close _resultSet;
end;
mysql> select * from user;
+----+----------+----------+---------+
| id | username | integral | ranking |
+----+----------+----------+---------+
| 1 | abc | 1 | 0 |
| 2 | abc | 2 | 0 |
| 3 | abc | 3 | 0 |
| 4 | abc | 4 | 0 |
| 5 | abc | 5 | 0 |
| 6 | abc | 6 | 0 |
| 7 | abc | 7 | 0 |
| 8 | abc | 8 | 0 |
| 9 | abc | 9 | 0 |
| 10 | abc | 10 | 0 |
| 11 | abc | 11 | 0 |
| 12 | abc | 12 | 0 |
| 13 | abc | 13 | 0 |
| 14 | abc | 14 | 0 |
+----+----------+----------+---------+
14 rows in set
mysql> call batchUpdate(14);
Query OK, 1 row affected
mysql> select * from user;
+----+----------+----------+---------+
| id | username | integral | ranking |
+----+----------+----------+---------+
| 1 | abc | 1 | 14 |
| 2 | abc | 2 | 13 |
| 3 | abc | 3 | 12 |
| 4 | abc | 4 | 11 |
| 5 | abc | 5 | 10 |
| 6 | abc | 6 | 9 |
| 7 | abc | 7 | 8 |
| 8 | abc | 8 | 7 |
| 9 | abc | 9 | 6 |
| 10 | abc | 10 | 5 |
| 11 | abc | 11 | 4 |
| 12 | abc | 12 | 3 |
| 13 | abc | 13 | 2 |
| 14 | abc | 14 | 1 |
+----+----------+----------+---------+
14 rows in set[/code]
drop PROCEDURE if EXISTS dealData;
CREATE PROCEDURE dealData()
BEGIN
DECLARE totalCount INT(10);
DECLARE i INT(10);
set totalCount =0; //记录数
set i=1;//排名
SELECT count(1) into totalCount from 表 ;
while(totalCount>0) DO
update 表 set 列=i where...;
set totalCount = totalCount-1;
set i = i +1;
end WHILE;
END;
CALL dealData();
可以利用自定义变量（MySQL）
[code="java"]drop PROCEDURE if exists dorank;
delimiter //
CREATE PROCEDURE dorank(IN N INT)
BEGIN
SET @i=0;
PREPARE s1 FROM '
update tiezi as a
inner join (
select @i := @i +1 as myrank, id, zan from tiezi order by zan desc limit ?
) as b
on a.id=b.id
set a.rank = b.myrank
';
set @a=N;
EXECUTE s1 USING @a;
DEALLOCATE PREPARE s1;
END;
//
delimiter ;
mysql> select * from tiezi;
+----+------+------+
| id | zan | rank |
+----+------+------+
| 1 | 100 | 0 |
| 2 | 300 | 0 |
| 3 | 50 | 0 |
+----+------+------+
3 rows in set (0.00 sec)
mysql> call dorank(2);
Query OK, 0 rows affected (0.00 sec)
mysql> select * from tiezi;
+----+------+------+
| id | zan | rank |
+----+------+------+
| 1 | 100 | 2 |
| 2 | 300 | 1 |
| 3 | 50 | 0 |
+----+------+------+
3 rows in set (0.00 sec)
[/code]