mysql存储过程开发中如何使用游标嵌套

在实际业务逻辑开发中，难免用到游标嵌套，举例如下：

delimiter //

drop procedure if exists good_nested_cursors1

//

CREATE   PROCEDURE good_nested_cursors1(  )

READS SQL DATA

BEGIN

DECLARE l_grade_id INT;

DECLARE l_class_id   INT;

DECLARE l_class_cnt     INT DEFAULT 0 ;

DECLARE l_done          INT DEFAULT  0;

DECLARE grade_csr cursor  FOR    SELECT grade_id FROM org_grade;

DECLARE class_csr cursor  FOR     SELECT class_id FROM org_class  WHERE grade_id=l_grade_id;

DECLARE CONTINUE HANDLER FOR NOT FOUND SET l_done=1;

OPEN grade_csr;

grade_loop: LOOP   -- Loop through org_grade

FETCH grade_csr into l_grade_id;

select concat('年级：', l_grade_id);

IF l_done=1 THEN

LEAVE grade_loop;

END IF;

OPEN class_csr;

SET l_class_cnt=0;

class_loop: LOOP      -- Loop through class in grade.

FETCH class_csr INTO l_class_id;

IF l_done=1 THEN

LEAVE class_loop;

END IF;

SET l_class_cnt=l_class_cnt+1;

select concat('    班级：', l_class_id);

END LOOP;

CLOSE class_csr;

SET l_done=0;

END LOOP grade_loop;

CLOSE grade_csr;

END;

//

delimiter ;

///

//另一个例子：

CREATE PROCEDURE curdemo()

NOT DETERMINISTIC

CONTAINS SQL

SQL SECURITY DEFINER

COMMENT ''

BEGIN

declare done1,done2 int default 0;

declare name1,name2 varchar(20);

declare id1,id2 int;

declare cur1 cursor for select id,name from test1;

declare continue handler for not found set done1 = 1;

open cur1;

repeat

fetch cur1 into id1, name1;

if not done1 then

insert into test3(name) values(name1);

begin

declare cur2 cursor for select id,name from test2;

declare continue handler for not found set done2 = 1;

open cur2;

repeat

fetch cur2 into id2,name2;

if not done2 then

insert into test3(name) values(name2);

end if;

until done2 end repeat;

close cur2;

set done2=0;

end;

end if;

until done1 end repeat;

close cur1;

commit;

END;

///

以上代码由达人礼品网提供

1楼aeolus_pu昨天 22:50

游标嵌套效率不太好吧

微信 赏一包辣条吧~

支付宝 赏一听可乐吧~