皇极惊世录txt,myeclipse8.5下载,福清中考
游标（cursor）相当于一条sql对应的结果集
声明一个游标
declare 游标名 cursor for select_statement
打开游标
open 游标名
取值
fetch 游标名 into var1，var2，[，var3...]
关闭一个游标
close 游标名
例1：
我要评论
mysql> delimiter //
mysql> create procedure demo1()
-> begin
-> declare c int;
-> declare n varchar(20);
-> declare total int default 0;
-> declare done int default false;
-> declare cur cursor for select username from users;
-> declare continue handler for not found set done=true;
-> set total=0;
-> open cur;
-> fetch cur into n;
-> while(not done) do
-> set total = total + 1;
-> fetch cur into n;
-> end while;
-> close cur;
-> select total;
-> end;
-> //
例2：
mysql> delimiter //
mysql> create procedure demo1()
-> begin
-> declare username varchar(20) default '';
-> declare cur1 cursor for select username from users;
-> declare continue handler for sqlstate '02000' set username=null;
-> open cur1;
-> fetch cur1 into username;
-> while (username is not null) do
-> set username = concat("hello",username);
-> fetch cur1 into username;
-> end while;
-> close cur1;
-> select username;
-> end;
-> //
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