MYSQL存储过程开发中怎么使用游标嵌套

本篇内容介绍了"MYSQL存储过程开发中怎么使用游标嵌套"的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

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;  www.2cto.com    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;  www.2cto.com    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;  www.2cto.com  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;///

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