MYSQL存儲過程開發中如何使用游標嵌套
在實際業務邏輯開發中，難免用到游標嵌套，舉例如下：
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;
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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('年級：', 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(' 班級：', l_class_id);
END LOOP;
CLOSE class_csr;
SET l_done=0;
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END LOOP grade_loop;
CLOSE grade_csr;
END;
//
delimiter ;
///////////////////////////////////////////////////////
//另一個例子：
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;
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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; www.2cto.com
until done2 end repeat;
close cur2;
set done2=0;
end;
end if;
until done1 end repeat;
close cur1;
commit;
END;
///
作者 蔡磊
