共计 2905 个字符,预计需要花费 8 分钟才能阅读完成。
这篇文章主要介绍“怎么理解数据库集合元素的删除”,在日常操作中,相信很多人在怎么理解数据库集合元素的删除问题上存在疑惑,丸趣 TV 小编查阅了各式资料,整理出简单好用的操作方法,希望对大家解答”怎么理解数据库集合元素的删除”的疑惑有所帮助!接下来,请跟着丸趣 TV 小编一起来学习吧!
我创建了一个嵌套表类型和过程:
CREATE OR REPLACE TYPE plch_numbers_t IS TABLE OF NUMBER;
CREATE OR REPLACE PROCEDURE plch_show_numbers (
title_in IN VARCHAR2
, numbers_in IN plch_numbers_t)
BEGIN
DBMS_OUTPUT.put_line (title_in);
FOR rec IN (SELECT COLUMN_VALUE FROM TABLE (numbers_in))
LOOP
DBMS_OUTPUT.put_line (rec.COLUMN_VALUE);
END LOOP;
/
下面的选项用来代替下列代码块的 /*BODY*/ 注释:
DECLARE
l_numbers plch_numbers_t
:= plch_numbers_t (12, 23, 34, 45, 56
, 67, 78, 89, 90, 100);
BEGIN
/*BODY*/
plch_show_numbers (AFTER DELETE , l_numbers);
/
哪些选项使得这个块执行之后会显示如下文本:
AFTER DELETE
89
换而言之,所有偶数元素都被删除了。
(A)
FOR indx IN 1 .. l_numbers.COUNT
IF MOD (indx, 2) = 0
THEN
l_numbers.delete (indx);
END IF;
END LOOP;
SQL DECLARE
2 l_numbers plch_numbers_t := plch_numbers_t(12,
3 23,
4 34,
5 45,
6 56,
7 67,
8 78,
9 89,
10 90,
11 100);
12 BEGIN
13 FOR indx IN 1 .. l_numbers.COUNT LOOP
14 IF MOD(indx, 2) = 0 THEN
15 l_numbers.delete(indx);
16 END IF;
17 END LOOP;
18
19 plch_show_numbers(AFTER DELETE , l_numbers);
20 END;
21 /
AFTER DELETE
PL/SQL procedure successfully completed
SQL
(B)
FOR indx IN 1 .. l_numbers.COUNT
IF MOD (l_numbers (indx), 2) = 0
THEN
l_numbers.delete (indx);
END IF;
END LOOP;
SQL DECLARE
2 l_numbers plch_numbers_t := plch_numbers_t(12,
3 23,
4 34,
5 45,
6 56,
7 67,
8 78,
9 89,
10 90,
11 100);
12 BEGIN
13 FOR indx IN 1 .. l_numbers.COUNT LOOP
14 IF MOD(l_numbers(indx), 2) = 0 THEN
15 l_numbers.delete(indx);
16 END IF;
17 END LOOP;
18
19 plch_show_numbers(AFTER DELETE , l_numbers);
20 END;
21 /
AFTER DELETE
PL/SQL procedure successfully completed
SQL
(C)
DELETE FROM TABLE (l_numbers)
WHERE MOD (index_value, 2) = 0;
SQL DECLARE
2 l_numbers plch_numbers_t := plch_numbers_t(12,
3 23,
4 34,
5 45,
6 56,
7 67,
8 78,
9 89,
10 90,
11 100);
12 BEGIN
13 DELETE FROM TABLE(l_numbers) WHERE MOD(index_value, 2) = 0;
14
15 plch_show_numbers(AFTER DELETE , l_numbers);
16 END;
17 /
DECLARE
l_numbers plch_numbers_t := plch_numbers_t(12,
23,
34,
45,
56,
67,
78,
89,
90,
100);
BEGIN
DELETE FROM TABLE(l_numbers) WHERE MOD(index_value, 2) = 0;
plch_show_numbers(AFTER DELETE , l_numbers);
ORA-06550: 第 13 行, 第 15 列:
PL/SQL: ORA-00903: 表名无效
ORA-06550: 第 13 行, 第 3 列:
PL/SQL: SQL Statement ignored
SQL
(D)
FOR rec IN (SELECT *
FROM TABLE (l_numbers)
WHERE MOD (COLUMN_VALUE, 2) = 0)
l_numbers.delete (rec.COLUMN_VALUE);
END LOOP;
SQL DECLARE
2 l_numbers plch_numbers_t := plch_numbers_t(12,
3 23,
4 34,
5 45,
6 56,
7 67,
8 78,
9 89,
10 90,
11 100);
12 BEGIN
13 FOR rec IN (SELECT * FROM TABLE(l_numbers) WHERE MOD(COLUMN_VALUE, 2) = 0) LOOP
14 l_numbers.delete(rec.COLUMN_VALUE);
15 END LOOP;
16
17 plch_show_numbers(AFTER DELETE , l_numbers);
18 END;
19 /
AFTER DELETE
PL/SQL procedure successfully completed
SQL
实测答案为 B
到此,关于“怎么理解数据库集合元素的删除”的学习就结束了,希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习,快去试试吧!若想继续学习更多相关知识,请继续关注丸趣 TV 网站,丸趣 TV 小编会继续努力为大家带来更多实用的文章!
正文完