MYSQL使用游标嵌套的两个实例
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 DATABEGIN 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;///作者 蔡磊
