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