PLSQL跳出嵌套循环的小例子

最新推荐文章于 2023-08-16 15:21:30 发布

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最新推荐文章于 2023-08-16 15:21:30 发布

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CC 4.0 BY-SA版权

原文链接：https://yq.aliyun.com/articles/359776

本文通过两个示例展示了PL/SQL中如何使用标签化的LOOP结构进行流程控制，包括如何实现内外循环以及如何通过条件判断来控制循环的退出。

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开始

DECLARE
   v_cnt NUMBER:=0;
   v_out_ext BOOLEAN:=FALSE;
   v_in_ext  BOOLEAN:=FALSE;
BEGIN
   <<Outer_loop>>
   LOOP
         
     EXIT WHEN v_cnt>20;

     <<Inner_loop>>
     LOOP
         dbms_output.put_line(v_cnt);
         v_cnt:=v_cnt+1;
         
         IF v_cnt>5 THEN
             v_in_ext:=TRUE;
         END IF;
         
         EXIT Outer_loop WHEN (v_in_ext = TRUE);         
     END LOOP; 
     dbms_output.put_line('++++++++++++++++++++');
   END LOOP;
END;

运行结果：

anonymous block completed
0
1
2
3
4
5

如果改成跳出内部循环：

DECLARE
   v_cnt NUMBER:=0;
   v_out_ext BOOLEAN:=FALSE;
   v_in_ext  BOOLEAN:=FALSE;
BEGIN
   <<Outer_loop>>
   LOOP
         
     EXIT WHEN v_cnt>20;

     <<Inner_loop>>
     LOOP
         dbms_output.put_line(v_cnt);
         v_cnt:=v_cnt+1;
         
         IF v_cnt>5 THEN
             v_in_ext:=TRUE;
         END IF;
         
         EXIT Inner_loop WHEN (v_in_ext = TRUE);         
     END LOOP; 
     dbms_output.put_line('++++++++++++++++++++');
   END LOOP;
END;

运行结果：

anonymous block completed
0
1
2
3
4
5
++++++++++++++++++++
6
++++++++++++++++++++
7
++++++++++++++++++++
8
++++++++++++++++++++
9
++++++++++++++++++++
10
++++++++++++++++++++
11
++++++++++++++++++++
12
++++++++++++++++++++
13
++++++++++++++++++++
14
++++++++++++++++++++
15
++++++++++++++++++++
16
++++++++++++++++++++
17
++++++++++++++++++++
18
++++++++++++++++++++
19
++++++++++++++++++++
20
++++++++++++++++++++