MySQL游标语法的用法

121次阅读

共计 1635 个字符，预计需要花费 5 分钟才能阅读完成。

本篇内容主要讲解“MySQL 游标语法的用法”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让丸趣 TV 小编来带大家学习“MySQL 游标语法的用法”吧!

1、基本语法：
Sql 代码
#定义游标
declare fetchSeqCursor cursor for select seqname, value from sys_sequence;
#使用游标
open fetchSeqCursor；
#fetch 数据
fetch cursor into _seqname, _value;
#关闭游标
close fetchSeqCursor;
2、单游标例子：
Sql 代码
## define the flag for loop judgement
declare fetchSeqOk boolean;
## define the varient for store the data
declare _seqname varchar(50);
declare _value bigint(20);
## define the cursor
declare fetchSeqCursor cursor for select seqname, value from sys_sequence;
## define the continue handler for not found flag
declare continue handler for NOT FOUND set fetchSeqOk = true;
set fetchSeqOk = false;
open fetchSeqCursor;
fetchSeqLoop:Loop
if fetchSeqOk then
leave fetchSeqLoop;
else
fetch cursor into _seqname, _value;
select _seqname, _value;
end if;
end Loop;
close fetchSeqCursor;
3、嵌套的游标循环
Java 代码
## define the flag for loop judgement
declare fetchSeqOk boolean;
## define the varient for store the data
declare _seqname varchar(50);
declare _value bigint(20);
## define the cursor
declare fetchSeqCursor cursor for select seqname, value from sys_sequence;
## define the continue handler for not found flag
declare continue handler for NOT FOUND set fetchSeqOk = true;
set fetchSeqOk = false;
open fetchSeqCursor;
fetchSeqLoop:Loop
if fetchSeqOk then
leave fetchSeqLoop;
else
fetch cursor into _seqname, _value;
#嵌套的游标循环
begin
declare fetchSeqOk boolean default inner
## define the cursor
declare cursor2 cursor for select …. from …;
## define the continue handler for not
declare continue handler for NOT FOUND set fetchSeqOk = true;
set fetchSeqOk = false;
open cursor2;
fetchloop2 loop
if fetchSeqOk then
else
end if;
end loop;
close cursor2;
end;
#嵌套的游标循环结束
end if;
end Loop;
close fetchSeqCursor;