Oracle与Mysql内嵌游标的使用示例

Posted 2020-10-23 哈比Sport

Oracle 游标用For循环比较简单，mysql也是最近才开始用，感觉稍微麻烦一点，下边直接上代码：

-----------------------------------------------------------
-- Oracle
-- 内嵌游标为带参游标，参数为外游标值
-----------------------------------------------------------
DECLARE
  cursor cur_outer is select dept_id from tbl_test_dept;
  cursor cur_inner(deptid varchar2) is (SELECT user_id FROM tbl_test_user WHERE dept_id=deptid);
  BEGIN
    FOR DEPT_ITEM IN cur_outer LOOP
              --
              --
         FOR KEY_ITEM IN cur_process(DEPT_ITEM.DEPT_ID) LOOP --开始内循环
              --
              --
         END LOOP;
    END LOOP;
  commit;
END;

------------------------------
-- Mysql
-- HANDLER 只能申明一个
-- 内循环结束后需要重置done
-- 发现mysql不能直接执行begin..end，需要创建存储过程后调用执行；
------------------------------
CREATE PROCEDURE `PROC_CURSOR_TEST`()
BEGIN
  DECLARE done INT DEFAULT FALSE;
  DECLARE item_outer VARCHAR(50);outer
  DECLARE item_inner VARCHAR(50);
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
  -- 定义内外游标
  DECLARE cur_outer cursor for select dept_id from tbl_test_dept;
  DECLARE cur_inner cursor for (SELECT user_id FROM tbl_test_user WHERE dept_id=item_outer);-- 查询条件可直接用外游标变量值

  OPEN cur_outer;
  out_loop: LOOP
    fetch cur_outer into item_outer;
      IF  done THEN -- 判断是否继续循环
        LEAVE out_loop;
      END IF;
        --
        --
    OPEN cur_process; -- 打开内嵌游标
    inner_loop: LOOP
    fetch cur_inner into item_inner;
      IF  done THEN
        LEAVE inner_loop;
      END IF;
        --
        --
    end loop;
    CLOSE cur_inner;
    SET done = 0;  -- 关闭内游标，重置done
  end loop;
  CLOSE cur_outer;
  commit;
END;
call PROC_CURSOR_TEST(); -- 调用存储过程
drop procedure PROC_CURSOR_TEST; --删除