plsql programming 11 记录类型
记录类型非常类似数据库表中的行. 记录作为一个整体本身并没有值, 不过每个单独成员或字段都有值, 记录提供了一种把这些值当做一组进行操作的方法.
例如:
1: -- create a table
2: -- chap11_01.sql
3: create table books (
4: book_id integer;
5: isbn varchar2(13),
6: title varchar2(200),
7: summary varchar2(2000),
8: author varchar2(200),
9: date_published DATE,
10: page_count number
11: );
12:
13: -- 方法1
14: -- chap11_02.sql
15: declare
16: my_book books%rowtype;
17: begin
18: select *
19: into my_book
20: from books
21: where title = 'oracle pl/sql programming, 5th Edition';
22:
23: if my_book.author like '%Feuerstein%'
24: then
25: dbms_output.put_line('Our newest ISBN is' || my_book.isbn);
26: end if;
27: exception
28: when no_data_found then
29: dbms_output.put_line('There is no data what you want it.');
30: end;
31: /
32:
33: -- 方法2
34: -- chap11_03.sql
35: declare
36: type author_title_rt is record (
37: author books.author%type,
38: title books.title%type);
39: l_book_info author_title_rt;
40: begin
41: select author, title into l_book_info
42: from books where isbn = '119'
43: dbms_output.put_line('author is : ' || l_book_info.author);
44: dbms_output.put_line('title : ' || l_book_info.title);
45: exception
46: when no_data_found then
47: dbms_output.putline('there is no data what you want');
48: end;
49: /
声明记录 3 种方式
1. 基于记录类型
declare one_book books%rowtype;
2. 基于游标记录类型
declare
cursor my_books_cur is
select * from books where author like ‘%FEUERSTEIN%’;
one_sf_book my_books_cur%rowtype;
3. 用户自定义的记录类型
例如上例中的方法 2 .
触发器伪记录
如果是在数据库触发器操作某个表, 数据库为我们提供了两种结构, OLD 和 NEW, 这两个结构是用 %rowtype声明的基于表的记录类型有相同的格式, 表中的每一列都有一个对应的字段:
OLD: 这条伪记录代表的是当前事务开始之前表中记录的值.
NEW: 这条伪记录代表的是当前事务结束之后, 表中记录的新值.