Sakila——MySQL樣例數據庫解析（已經遷移）

一、Introduction

Sakila可以作為數據庫設計的參考,也可作為實驗數據。我是用作數據倉庫和ODI學習的實驗數據。

The Sakila sample database was developed by Mike Hillyer, a former member of the MySQL AB documentation team, and is intended to provide a standard schema that can be used for examples in books, tutorials, articles, samples, and so forth. Sakila sample database also serves to highlight the latest features of MySQL such as Views, Stored Procedures, and Triggers.

二、Installation

方法一：安裝MySQL時選擇 FULL 完全安裝

安裝MySQL時選擇FULL 完全安裝, 默認安裝了Sakila sample database

方法二：下載后導入

The Sakila sample database is available from http://dev.mysql.com/doc/index-other.html. A downloadable archive is available in compressed file or Zip format. The archive contains three files: sakila-schema.sql, sakila-data.sql, and sakila.mwb.

The sakila-schema.sql file contains all the CREATE statements required to create the structure of the Sakila database including tables, views, stored procedures, and triggers.

The sakila-data.sql file contains the INSERT statements required to populate the structure created by the sakila-schema.sql file, along with definitions for triggers that must be created after the initial data load.

The sakila.mwb file is a MySQL Workbench data model that you can open within MySQL Workbench to examine the database structure. For more information, see MySQL Workbench.

下載地址：

ZIP格式：http://downloads.mysql.com/docs/sakila-db.zip

tar格式  http://downloads.mysql.com/docs/sakila-db.tar.gz

官方文檔 http://dev.mysql.com/doc/sakila/en/index.html

解壓后得到三個文件：

1. sakila-schema.sql 文件包含創建Sakila數據庫的結構：表、視圖、存儲過程和觸發器

2. sakila-data.sql文件包含：使用 INSERT語句填充數據及在初始數據加載后，必須創建的觸發器的定義

3. sakila.mwb文件是一個MySQL Workbench數據模型，可以在MySQL的工作台打開查看數據庫結構。

導入參考： http://dev.mysql.com/doc/sakila/en/sakila-installation.html

   shell> mysql -u root -p

mysql> SOURCE C:/temp/sakila-db/sakila-schema.sql;

mysql> SOURCE C:/temp/sakila-db/sakila-data.sql;

查看導入結果

三、Structure

 

Sakila樣例數據庫包括16張表格，7個視圖，3個Stored Procedures，3個Functions，6個Triggers。英文描述點開相應連接即可查看。

全圖：

 

Customer Data 和 Business Data

Inventory Data

3.1 Tables

3.1.1. The actor Table 演員表

3.1.2. The address Table 地址表

3.1.3. The category Table 電影類別表

3.1.4. The city Table 城市表

3.1.5. The country Table 國家表

3.1.6. The customer Table 客戶表

3.1.7. The film Table 電影表

3.1.8. The film_actor Table 電影和演員中間對應表

3.1.9. The film_category Table 電影和類別的中間對應表

3.1.10. The film_text Table 只包含title和description兩列的電影表子表，用以快速檢索

3.1.11. The inventory Table 庫存表

3.1.12. The language Table 語言表

3.1.13. The payment Table 付款表

3.1.14. The rental Table 租金表

3.1.15. The staff Table 工作人員表

3.1.16. The store Table 商店表

【01 演員表 actor】

演員表列出了所有演員的信息。演員表和電影表之間是多對多的關系，通過film_actor表建立關系

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actor_id: 代理主鍵用於唯一標識表中的每個演員 first_name: 演員的名字 last_name: 演員的姓氏 last_update: 該行已創建或最近更新的時間

【02 地址表 address】

地址表包含客戶、員工和商店的地址信息。地址表的主鍵出現在顧客、 員工、和存儲表的外鍵 。

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address_id: 代理主鍵用於唯一標識表中的每個地址 address: 地址的第一行 address2: 一個可選的第二行地址 district: 該地區的所屬地區，這可以是國家，省，縣等 city_id: 指向城市表的外鍵 postal_code: 郵政編碼 phone: 地址的電話號碼 last_update: 該行已創建或最近更新的時間

【03 分類表 category】

類別表列出了可以分配到一個電影類別。分類和電影是多對多的關系，通過表film_category建立關系

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category_id: 代理主鍵用於唯一標識表中的每個類別 name: 類別名稱 last_update: 該行已創建或最近更新的時間

【04 城市表 city】

城市表包含的城市名單。城市表使用外鍵來標示國家；在地址表中被作為外鍵來使用。

1 2 3 4

city_id: 代理主鍵用於唯一標識表中的每個城市 city: 城市的名字 country_id: 外鍵，用於標示城市所屬的國家 last_update: 該行已創建或最近更新的時間

【05 國家表 country】

國家表中包含的國家名單。國家表是指在城市表的外鍵 。

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country_id: 代理主鍵用於唯一標識表中的每個國家 country: 國家的名稱 last_update: 該行已創建或最近更新的時間

【06 客戶表 customer】

客戶表包含了所有客戶的列表 。 客戶表在支付表和租金表被作為外鍵使用；客戶表使用外鍵來表示地址和存儲。

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customer_id: 代理主鍵用於唯一標識表中的每個客戶 store_id: 一個外鍵，確定客戶所屬的store。 first_name: 客戶的名字 last_name: 客戶的姓氏 email: 客戶的電子郵件地址 address_id: 使用在地址 表的外鍵來確定客戶的地址 active: 表示客戶是否是活躍的客戶 create_date: 顧客被添加到系統中的日期。使用 INSERT 觸發器自動設置。 last_update: 該行已創建或最近更新的時間

說明：
active: 此設置為“ FALSE“作為替代客戶徹底刪除。大多數查詢應該有一個 WHERE active = TRUE 字句。
store_id: 此處的客戶不僅限於只由這家商店出租，而是包括客戶常常去逛的商店

【07 電影表 film】

電影表是一個可能在商店庫存的所有影片名單。每部影片的拷貝的實際庫存信息保存在庫存表。電影表指使用外鍵來標示語言表；在film_category、film_actor和庫存表中作為外鍵使用。

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film_id: 代理主鍵用於唯一標識表中的每個電影 title: 影片的標題 description: 一個簡短的描述或電影的情節摘要 release_year: 電影發行的年份 language_id: 使用外鍵來標示語言 original_language_id: 電影的原始語音。使用外鍵來標示語言 rental_duration: 租賃期限的長短，以天作為單位 rental_rate: 指定的期限內電影的租金 length: 影片的長度，以分鍾為單位。 replacement_cost: 如果電影未被歸還或損壞狀態向客戶收取的款項 rating: 分配給電影評級。可以是 G， PG，PG - 13 ， R 或NC - 17 special_features: 包括DVD上常見的特殊功能的列表 last_update: 該行已創建或最近更新的時間

特殊功能包括零個或多個拖車、評論、刪剪片段、幕后。

【08  film_actor表】

film_actor表是用來支持許多電影和演員之間的多對多關系 。對於每一個給定的電影演員，將有film_actor表中列出的演員和電影中的一個行 。

film_actor表指的是使用外鍵的電影和演員表。

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actor_id: 用於識別演員的外鍵 film_id: 用於識別電影的外鍵 last_update: 該行已創建或最近更新的時間

【09  film_category表】

film_category表是用來支持許多電影和類別之間的多對多關系 。應用於電影的每個類別中，將有film_category表中列出的類別和電影中的一個行。

film_category表是指使用外鍵 的 電影 和類別表 。

1 2 3

film_id: 用於識別電影的外鍵 category_id: 用於識別類別的外鍵 last_update: 該行已創建或最近更新的時間

【10  film_text表】

film_text表是Sakila樣例數據庫唯一使用MyISAM存儲引擎的表。MyISAM類型不支持事務處理等高級處理，而InnoDB類型支持。MyISAM類型的表強調的是性能，其執行數度比InnoDB類型更快。此表提供允許全文搜索電影表中列出的影片的標題和描述。film_text表包含的film_id，標題和描述的列電影表，保存的內容與電影表上的內容同步（指電影表的插入、更新和刪除操作）

1 2 3

film_id: 代理主鍵用於唯一標識表中的每個電影 title: 影片的標題 description: 一個簡短的描述或電影的情節摘要

注意：film_text表的內容不應該直接修改。所有的變更來自於電影表 。

【11 庫存表 inventory】

庫存表的一行為存放在一個給定的商店里的一個給定的電影的copy副本。庫存表是使用外鍵來識別電影和存儲；在出租表中使用外鍵來識別庫存。

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inventory_id: 理主鍵用於唯一標識每個項目在庫存 film_id: 使用外鍵來識別電影 store_id: 使用外鍵來識別物品所在的商店 last_update: 該行已創建或最近更新的時間

【12 語言表 language】

語言表是一個查找表，列出可能使用的語言，電影可以有自己的語言和原始語言值 。

語言表在電壓表中被作為外鍵來使用。

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language_id: 代理主鍵用於唯一標識每一種語言 name: 語言的英文名稱 last_update: 該行已創建或最近更新的時間

【13   付款表 payment】

付款表記錄每個客戶的付款，如支付的金額和租金的資料。

付款表使用外鍵來表示客戶、出租、和工作人員。

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payment_id: 代理主鍵用於唯一標識每個付款 customer_id: 使用外鍵來標識付款的客戶 staff_id: 工作人員，負責處理支付 。使用外鍵來標識 rental_id: 租借ID, 外鍵，參照rental表 amount: 付款金額 payment_date: 處理付款的日期 last_update: 該行已創建或最近更新的時間

【14 租金表 rental】

租借表的一行表示每個inventory的租借客戶、租借時間、歸還時間

租借表是使用外鍵來標識庫存 ，顧客 和工作人員；在支付表中使用了外鍵來標識租金 。

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rental_id: 代理主鍵唯一標識的租金 rental_date: 該項目租用的日期和時間 inventory_id: 該項目被租用 customer_id: 租用該項目的客戶 return_date: 歸還日期 staff_id: 處理該項業務的工作人員 last_update: 該行已創建或最近更新的時間

【15 工作人員表 staff】

工作人員表列出了所有的工作人員，包括電子郵件地址，登錄信息和圖片信息 。

工作人員表是指使用外鍵來標識存儲和地址表；在出租、支付和商店表中作為外鍵。

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staff_id: 代理主鍵唯一標識的工作人員 first_name: 工作人員的名字 last_name: 工作人員的姓氏 address_id: 工作人員的地址在地址表的外鍵 picture: 工作人員的照片，使用了 BLOB屬性 email: 工作人員的電子郵件地址 store_id: 工作人員所在的商店，用外鍵標識 active: 是否是活躍的工作人員。 username: 用戶名，由工作人員用來訪問租賃系統 password: 工作人員訪問租賃系統所使用的密碼。使用了 SHA1 函數 last_update: 該行已創建或最近更新的時間 active: 是否有效，刪除時設置為False

【16 商店表 store】

store表列出了系統中的所有商店 。

store使用外鍵來標識工作人員和地址；在員工、客戶、庫存表被作為外鍵使用。

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store_id: 代理主鍵唯一標識的商店 manager_staff_id: 使用外鍵來標識這家商店的經理 address_id: 使用外鍵來確定這家店的地址 last_update: 該行已創建或最近更新的時間

3.2 Views

3.2.1. The actor_info View

actor_info 視圖提供了所有演員的列表及所演的電影, 電影按category分組.

 actor → film_actor → film →  film_category → category

SELECT
a.actor_id,
a.first_name,
a.last_name,
GROUP_CONCAT(DISTINCT CONCAT(c.name, ': ',
        (SELECT GROUP_CONCAT(f.title ORDER BY f.title SEPARATOR ', ')
                    FROM sakila.film f
                    INNER JOIN sakila.film_category fc
                      ON f.film_id = fc.film_id
                    INNER JOIN sakila.film_actor fa
                      ON f.film_id = fa.film_id
                    WHERE fc.category_id = c.category_id
                    AND fa.actor_id = a.actor_id
                 )
             )
             ORDER BY c.name SEPARATOR '; ')
AS film_info
FROM sakila.actor a
LEFT JOIN sakila.film_actor fa
  ON a.actor_id = fa.actor_id
LEFT JOIN sakila.film_category fc
  ON fa.film_id = fc.film_id
LEFT JOIN sakila.category c
  ON fc.category_id = c.category_id
GROUP BY a.actor_id, a.first_name, a.last_name

3.2.2. The customer_list View

客戶列表，firstname和lastname連接成fullname，將 address, city, country 集成在一個視圖里

customer → address → city → country

SELECT
    cu.customer_id AS ID,
    CONCAT(
        cu.first_name,
        _utf8 ' ',
        cu.last_name
    ) AS NAME,
    a.address AS address,
    a.postal_code AS `zip code`,
    a.phone AS phone,
    city.city AS city,
    country.country AS country,

IF (
    cu.active,
    _utf8 'active',
    _utf8 ''
) AS notes,
 cu.store_id AS SID
FROM
    customer AS cu
JOIN address AS a ON cu.address_id = a.address_id
JOIN city ON a.city_id = city.city_id
JOIN country ON city.country_id = country.country_id

3.2.3. The film_list View

電影列表視圖，包含了每一部電影的信息及電影所對應的演員。電影對應的演員以逗號作為分隔符。連接了 film, film_category, category,film_actor and actor 表的數據

SELECT
    film.film_id AS FID,
    film.title AS title,
    film.description AS description,
    category. NAME AS category,
    film.rental_rate AS price,
    film.length AS length,
    film.rating AS rating,
    GROUP_CONCAT(
        CONCAT(
            actor.first_name,
            _utf8 ' ',
            actor.last_name
        ) SEPARATOR ', '
    ) AS actors
FROM
    category
LEFT JOIN film_category ON category.category_id = film_category.category_id
LEFT JOIN film ON film_category.film_id = film.film_id
JOIN film_actor ON film.film_id = film_actor.film_id
JOIN actor ON film_actor.actor_id = actor.actor_id
GROUP BY
    film.film_id

3.2.4. The nicer_but_slower_film_list View

電影列表視圖，包含了每一部電影的信息及電影所對應的演員。電影對應的演員以逗號作為分隔符。連接了 film, film_category, category,film_actor and actor 表的數據。和The film_list View不同，演員名字只有單詞首字母大寫了。

SELECT
    film.film_id AS FID,
    film.title AS title,
    film.description AS description,
    category. NAME AS category,
    film.rental_rate AS price,
    film.length AS length,
    film.rating AS rating,
    GROUP_CONCAT(
        CONCAT(
            CONCAT(
                UCASE(
                    SUBSTR(actor.first_name, 1, 1)
                ),
                LCASE(
                    SUBSTR(
                        actor.first_name,
                        2,
                        LENGTH(actor.first_name)
                    )
                ),
                _utf8 ' ',
                CONCAT(
                    UCASE(
                        SUBSTR(actor.last_name, 1, 1)
                    ),
                    LCASE(
                        SUBSTR(
                            actor.last_name,
                            2,
                            LENGTH(actor.last_name)
                        )
                    )
                )
            )
        ) SEPARATOR ', '
    ) AS actors
FROM
    category
LEFT JOIN film_category ON category.category_id = film_category.category_id
LEFT JOIN film ON film_category.film_id = film.film_id
JOIN film_actor ON film.film_id = film_actor.film_id
JOIN actor ON film_actor.actor_id = actor.actor_id
GROUP BY
    film.film_id

3.2.5. The sales_by_film_category View

每個電影種類的銷售額 , payment → rental → inventory → film → film_category → category 

SELECT
c.name AS category
, SUM(p.amount) AS total_sales
FROM payment AS p
INNER JOIN rental AS r ON p.rental_id = r.rental_id
INNER JOIN inventory AS i ON r.inventory_id = i.inventory_id
INNER JOIN film AS f ON i.film_id = f.film_id
INNER JOIN film_category AS fc ON f.film_id = fc.film_id
INNER JOIN category AS c ON fc.category_id = c.category_id
GROUP BY c.name
ORDER BY total_sales DESC

3.2.6. The sales_by_store View

每個商店的manager及銷售額。

payment → rental → inventory → store → staff

SELECT
CONCAT(c.city, _utf8',', cy.country) AS store
, CONCAT(m.first_name, _utf8' ', m.last_name) AS manager
, SUM(p.amount) AS total_sales
FROM payment AS p
INNER JOIN rental AS r ON p.rental_id = r.rental_id
INNER JOIN inventory AS i ON r.inventory_id = i.inventory_id
INNER JOIN store AS s ON i.store_id = s.store_id
INNER JOIN address AS a ON s.address_id = a.address_id
INNER JOIN city AS c ON a.city_id = c.city_id
INNER JOIN country AS cy ON c.country_id = cy.country_id
INNER JOIN staff AS m ON s.manager_staff_id = m.staff_id
GROUP BY s.store_id
ORDER BY cy.country, c.city

3.2.7. The staff_list View

工作人員的列表

SELECT
    s.staff_id AS ID,
    CONCAT(
        s.first_name,
        _utf8 ' ',
        s.last_name
    ) AS NAME,
    a.address AS address,
    a.postal_code AS `zip code`,
    a.phone AS phone,
    city.city AS city,
    country.country AS country,
    s.store_id AS SID
FROM
    staff AS s
JOIN address AS a ON s.address_id = a.address_id
JOIN city ON a.city_id = city.city_id
JOIN country ON city.country_id = country.country_id

3.3 Stored Procedures

3.3.1. The film_in_stock Stored Procedure

Description

The film_in_stock stored procedure is used to determine whether any copies of a given film are in stock at a given store.

判斷在一個給定的商店里是否有一個給定電影的copy.

Parameters

• p_film_id: The ID of the film to be checked, from the film_id column of the film table.

• p_store_id: The ID of the store to check for, from the store_id column of the store table.

• p_film_count: An OUT parameter that returns a count of the copies of the film in stock.

Return Values

This procedure produces a table of inventory ID numbers for the copies of the film in stock, and returns (in the p_film_count parameter) a count that indicates the number of rows in that table.

BEGIN
     SELECT inventory_id
     FROM inventory
     WHERE film_id = p_film_id
     AND store_id = p_store_id
     AND inventory_in_stock(inventory_id);

     SELECT FOUND_ROWS() INTO p_film_count;
END

3.3.2. The film_not_in_stock Stored Procedure

和The film_in_stock Stored Procedure相反，判斷給定的電影，是否有copy，不在一個給定的商店

Description

The film_not_in_stock stored procedure is used to determine whether there are any copies of a given film not in stock (rented out) at a given store.

Parameters

• p_film_id: The ID of the film to be checked, from the film_id column of the film table.

• p_store_id: The ID of the store to check for, from the store_id column of the store table.

• p_film_count: An OUT parameter that returns a count of the copies of the film not in stock.

Return Values

This procedure produces a table of inventory ID numbers for the copies of the film not in stock, and returns (in the p_film_count parameter) a count that indicates the number of rows in that table.

BEGIN
     SELECT inventory_id
     FROM inventory
     WHERE film_id = p_film_id
     AND store_id = p_store_id
     AND NOT inventory_in_stock(inventory_id);

     SELECT FOUND_ROWS() INTO p_film_count;
END

3.3.3. The rewards_report Stored Procedure

過去一個月，數量大於輸入參數min_monthly_purchases ，消費金額大於輸入參數min_dollar_amount_purchased的客戶

Description

The rewards_report stored procedure generates a customizable list of the top customers for the previous month.

Parameters

• min_monthly_purchases: The minimum number of purchases or rentals a customer needed to make in the last month to qualify.

• min_dollar_amount_purchased: The minimum dollar amount a customer needed to spend in the last month to qualify.

• count_rewardees: An OUT parameter that returns a count of the customers who met the qualifications specified.

Return Values

This function returns a table of customers who met the qualifications specified. The table has the same structure as the customer table. The procedure also returns (in the count_rewardees parameter) a count that indicates the number of rows in that table.

Stop Service         net stop uxsms

Start Service         net start uxsms

Disable Service     sc config uxsms start= disabled

Enable Service      sc config uxsms start= auto

proc: BEGIN

    DECLARE last_month_start DATE;
    DECLARE last_month_end DATE;

    /* Some sanity checks... */
    IF min_monthly_purchases = 0 THEN
        SELECT 'Minimum monthly purchases parameter must be > 0';
        LEAVE proc;
    END IF;
    IF min_dollar_amount_purchased = 0.00 THEN
        SELECT 'Minimum monthly dollar amount purchased parameter must be > $0.00';
        LEAVE proc;
    END IF;

    /* Determine start and end time periods */
    SET last_month_start = DATE_SUB(CURRENT_DATE(), INTERVAL 1 MONTH);
    SET last_month_start = STR_TO_DATE(CONCAT(YEAR(last_month_start),'-',MONTH(last_month_start),'-01'),'%Y-%m-%d');
    SET last_month_end = LAST_DAY(last_month_start);

    /*
        Create a temporary storage area for
        Customer IDs.
    */
    CREATE TEMPORARY TABLE tmpCustomer (customer_id SMALLINT UNSIGNED NOT NULL PRIMARY KEY);

    /*
        Find all customers meeting the
        monthly purchase requirements
    */
    INSERT INTO tmpCustomer (customer_id)
    SELECT p.customer_id
    FROM payment AS p
    WHERE DATE(p.payment_date) BETWEEN last_month_start AND last_month_end
    GROUP BY customer_id
    HAVING SUM(p.amount) > min_dollar_amount_purchased
    AND COUNT(customer_id) > min_monthly_purchases;

    /* Populate OUT parameter with count of found customers */
    SELECT COUNT(*) FROM tmpCustomer INTO count_rewardees;

    /*
        Output ALL customer information of matching rewardees.
        Customize output as needed.
    */
    SELECT c.*
    FROM tmpCustomer AS t
    INNER JOIN customer AS c ON t.customer_id = c.customer_id;

    /* Clean up */
    DROP TABLE tmpCustomer;
END

因為不滿足系統時間，所以結果為0

3.4 Stored Functions

3.4.1. The get_customer_balance Function

返回指定客戶到某一個日期欠的錢。 所有的rental_rate +超期費用 - 所有的payment

Description

The get_customer_balance function returns the current amount owing on a specified customer's account.

Parameters

• p_customer_id: The ID of the customer to check, from the customer_id column of the customer table.

• p_effective_date: The cutoff date for items that will be applied to the balance. Any rentals, payments, and so forth after this date are not counted.

Return Values

This function returns the amount owing on the customer's account.

BEGIN

       #OK, WE NEED TO CALCULATE THE CURRENT BALANCE GIVEN A CUSTOMER_ID AND A DATE
       #THAT WE WANT THE BALANCE TO BE EFFECTIVE FOR. THE BALANCE IS:
       #   1) RENTAL FEES FOR ALL PREVIOUS RENTALS
       #   2) ONE DOLLAR FOR EVERY DAY THE PREVIOUS RENTALS ARE OVERDUE
       #   3) IF A FILM IS MORE THAN RENTAL_DURATION * 2 OVERDUE, CHARGE THE REPLACEMENT_COST
       #   4) SUBTRACT ALL PAYMENTS MADE BEFORE THE DATE SPECIFIED

  DECLARE v_rentfees DECIMAL(5,2); #FEES PAID TO RENT THE VIDEOS INITIALLY
  DECLARE v_overfees INTEGER;      #LATE FEES FOR PRIOR RENTALS
  DECLARE v_payments DECIMAL(5,2); #SUM OF PAYMENTS MADE PREVIOUSLY

  SELECT IFNULL(SUM(film.rental_rate),0) INTO v_rentfees
    FROM film, inventory, rental
    WHERE film.film_id = inventory.film_id
      AND inventory.inventory_id = rental.inventory_id
      AND rental.rental_date <= p_effective_date
      AND rental.customer_id = p_customer_id;

  SELECT IFNULL(SUM(IF((TO_DAYS(rental.return_date) - TO_DAYS(rental.rental_date)) > film.rental_duration,
        ((TO_DAYS(rental.return_date) - TO_DAYS(rental.rental_date)) - film.rental_duration),0)),0) INTO v_overfees
    FROM rental, inventory, film
    WHERE film.film_id = inventory.film_id
      AND inventory.inventory_id = rental.inventory_id
      AND rental.rental_date <= p_effective_date
      AND rental.customer_id = p_customer_id;


  SELECT IFNULL(SUM(payment.amount),0) INTO v_payments
    FROM payment

    WHERE payment.payment_date <= p_effective_date
    AND payment.customer_id = p_customer_id;

  RETURN v_rentfees + v_overfees - v_payments;
END

3.4.2. The inventory_held_by_customer Function

返回指定的inventory現在在那個客戶的customer_id 

The inventory_held_by_customer function returns the customer_id of the customer who has rented out the specified inventory item.

Parameters

• p_inventory_id: The ID of the inventory item to be checked.

Return Values

This function returns the customer_id of the customer who is currently renting the item, or NULL if the item is in stock.

BEGIN
  DECLARE v_customer_id INT;
  DECLARE EXIT HANDLER FOR NOT FOUND RETURN NULL;

  SELECT customer_id INTO v_customer_id
  FROM rental
  WHERE return_date IS NULL
  AND inventory_id = p_inventory_id;

  RETURN v_customer_id;
END

3.4.3. The inventory_in_stock Function

返回指定的inventory是否在商店里

The inventory_in stock function returns a boolean value indicating whether the inventory item specified is in stock.

Parameters

• p_inventory_id: The ID of the inventory item to be checked.

Return Values

This function returns TRUE or FALSE to indicate whether the item specified is in stock.

BEGIN
    DECLARE v_rentals INT;
    DECLARE v_out     INT;

    #AN ITEM IS IN-STOCK IF THERE ARE EITHER NO ROWS IN THE rental TABLE
    #FOR THE ITEM OR ALL ROWS HAVE return_date POPULATED

    SELECT COUNT(*) INTO v_rentals
    FROM rental
    WHERE inventory_id = p_inventory_id;

    IF v_rentals = 0 THEN
      RETURN TRUE;
    END IF;

    SELECT COUNT(rental_id) INTO v_out
    FROM inventory LEFT JOIN rental USING(inventory_id)
    WHERE inventory.inventory_id = p_inventory_id
    AND rental.return_date IS NULL;

    IF v_out > 0 THEN
      RETURN FALSE;
    ELSE
      RETURN TRUE;
    END IF;
END

3.5 Triggers

3.5.1. The customer_create_date Trigger

插入新客戶時，設置create_date為當前日期

-- Trigger to enforce create dates on INSERT

CREATE TRIGGER customer_create_date BEFORE INSERT ON customer
    FOR EACH ROW SET NEW.create_date = NOW();

3.5.2. The payment_date Trigger

payment新增記錄時，payment_date設置為當前日期

-- Trigger to enforce payment_date during INSERT

CREATE TRIGGER payment_date BEFORE INSERT ON payment
    FOR EACH ROW SET NEW.payment_date = NOW();

3.5.3. The rental_date Trigger

rental表新增記錄時，rental_date設置為當前日期

-- Trigger to enforce rental_date on INSERT

CREATE TRIGGER rental_date BEFORE INSERT ON rental
    FOR EACH ROW SET NEW.rental_date = NOW();

3.5.4. The ins_film Trigger

確保 film_text 和 film同步插入

CREATE TRIGGER `ins_film` AFTER INSERT ON `film` FOR EACH ROW BEGIN
    INSERT INTO film_text (film_id, title, description)
        VALUES (new.film_id, new.title, new.description);
  END;;

3.5.5. The upd_film Trigger

確保 film_text 和 film同步更新

CREATE TRIGGER `upd_film` AFTER UPDATE ON `film` FOR EACH ROW BEGIN
    IF (old.title != new.title) OR (old.description != new.description) OR (old.film_id != new.film_id)
    THEN
        UPDATE film_text
            SET title=new.title,
                description=new.description,
                film_id=new.film_id
        WHERE film_id=old.film_id;
    END IF;
  END;;

3.5.6. The del_film Trigger

確保 film_text 和 film同步刪除

CREATE TRIGGER `del_film` AFTER DELETE ON `film` FOR EACH ROW BEGIN
    DELETE FROM film_text WHERE film_id = old.film_id;
  END;;