《oracle pl/sql programming》 第11章 record

record

record表示一個記錄類型。舉例：
創建一個表：
CREATE TABLE books (
book_id INTEGER,
isbn VARCHAR2(13),
title VARCHAR2(200),
summary VARCHAR2(2000),
author VARCHAR2(200),
date_published DATE,
page_count NUMBER
);
利用record取得這個表的數據：
DECLARE
my_book books%ROWTYPE;
BEGIN
SELECT *
INTO my_book
FROM books
WHERE title = 'Oracle PL/SQL Programming, 4th Edition';

IF my_book.author LIKE '%Feuerstein%'
THEN
DBMS_OUTPUT.put_line ('Our newest ISBN is ' || my_book.isbn);
END IF;
END;

有三種類型的record,分別是：
基于表的record;
基于cursor的record;
自定義record;
上例中的my_book是基于表的record;
如下是基于cursor的record:
DECLARE
CURSOR my_books_cur IS
SELECT * FROM books
WHERE author LIKE '%FEUERSTEIN%';

one_SF_book my_books_cur%ROWTYPE;
如下是一個癮式的基于游標的record應用：
BEGIN
FOR book_rec IN (SELECT * FROM books)
LOOP
calculate_total_sales (book_rec);
END LOOP;
END;
如下是自定義的record:
DECLARE
TYPE book_info_rt IS RECORD (
author books.author%TYPE,
category VARCHAR2(100),
total_page_count POSITIVE);

steven_as_author book_info_rt;

通過.操作符來訪問record的字段值，如：
DECLARE
rain_forest_rec rain_forest_history%ROWTYPE;
BEGIN
/* Set values for the record */
rain_forest_rec.country_code := 1005;
rain_forest_rec.analysis_date :=
ADD_MONTHS (TRUNC (SYSDATE), -3);
rain_forest_rec.size_in_acres := 32;
rain_forest_rec.species_lost := 425;

/* Insert a row in the table using the record values */
INSERT INTO rain_forest_history
(country_code, analysis_date, size_in_acres, species_lost)
VALUES
(rain_forest_rec.country_code,
rain_forest_rec.analysis_date,
rain_forest_rec.size_in_acres,
rain_forest_rec.species_lost);
...
END;

嵌套游標，如下：
DECLARE
TYPE phone_rectype IS RECORD
(intl_prefix VARCHAR2(2),
area_code VARCHAR2(3),
exchange VARCHAR2(3),
phn_number VARCHAR2(4),
extension VARCHAR2(4)
);

-- Each field is a nested record...
TYPE contact_set_rectype IS RECORD
(day_phone# phone_rectype,
eve_phone# phone_rectype,
fax_phone# phone_rectype,
home_phone# phone_rectype,
cell_phone# phone_rectype
);

auth_rep_info_rec contact_set_rectype;
BEGIN
...
auth_rep_info_rec.fax_phone#.area_code :=
auth_rep_info_rec.home_phone#.area_code;

record的比較,你不能直接用=比較，這樣是不行的：
DECLARE
first_book summer.reading_list_rt := summer.must_read;
second_book summer.reading_list_rt := summer.wifes_favorite;
BEGIN
IF first_book = second_book
THEN
lots_to_talk_about;
END IF;
END;
而應該這樣：
DECLARE
first_book summer.reading_list_rt := summer.must_read;
second_book summer.reading_list_rt := summer.wifes_favorite;
BEGIN
IF first_book.favorite_author = second_book.favorite_author
AND first_book.title = second_book.title
AND first_book.finish_by = second_book.finish_by
THEN
lots_to_talk_about;
END IF;
END;

觸發器里的Pseudo-Records
在觸發器里，提供了OLD和NEW這兩個record,OLD變數記錄修改前的值，NEW表示記錄修改后的值，它們被稱為Pseudo-Records。如下例：
CREATE OR REPLACE TRIGGER check_raise
AFTER UPDATE OF salary
ON employee
FOR EACH ROW
WHEN (OLD.salary != NEW.salary) OR
(OLD.salary IS NULL AND NEW.salary IS NOT NULL) OR
(OLD.salary IS NOT NULL AND NEW.salary IS NULL)
BEGIN
IF :NEW.salary > 100000 THEN ...