字段	说明
category_id	电影分类id
name	电影分类名称
last_update	电影分类最后更新时间

film_category表

CREATE TABLE film_category  (

film_id  smallint(5)  NOT NULL,

category_id  tinyint(3)  NOT NULL, `last_update` timestamp);

示例1

输入:

drop table if exists   film ;
drop table if exists  category  ; 
drop table if exists  film_category  ; 
CREATE TABLE IF NOT EXISTS film (
  film_id smallint(5)  NOT NULL DEFAULT '0',
  title varchar(255) NOT NULL,
  description text,
  PRIMARY KEY (film_id));
CREATE TABLE category  (
   category_id  tinyint(3)  NOT NULL ,
   name  varchar(25) NOT NULL, `last_update` timestamp,
  PRIMARY KEY ( category_id ));
CREATE TABLE film_category  (
   film_id  smallint(5)  NOT NULL,
   category_id  tinyint(3)  NOT NULL, `last_update` timestamp);
INSERT INTO film VALUES(1,'ACADEMY DINOSAUR','A Epic Drama of a Feminist And a Mad Scientist who must Battle a Teacher in The Canadian Rockies');
INSERT INTO film VALUES(2,'ACE GOLDFINGER','A Astounding Epistle of a Database Administrator And a Explorer who must Find a Car in Ancient China');
INSERT INTO film VALUES(3,'ADAPTATION HOLES','A Astounding Reflection of a Lumberjack And a Car who must Sink a Lumberjack in A Baloon Factory');

INSERT INTO category VALUES(1,'Action','2006-02-14 20:46:27');
INSERT INTO category VALUES(2,'Animation','2006-02-14 20:46:27');
INSERT INTO category VALUES(3,'Children','2006-02-14 20:46:27');
INSERT INTO category VALUES(4,'Classics','2006-02-14 20:46:27');
INSERT INTO category VALUES(5,'Comedy','2006-02-14 20:46:27');
INSERT INTO category VALUES(6,'Documentary','2006-02-14 20:46:27');

INSERT INTO film_category VALUES(1,1,'2006-02-14 21:07:09');
INSERT INTO film_category VALUES(2,1,'2006-02-14 21:07:09');
INSERT INTO film_category VALUES(3,6,'2006-02-14 21:07:09');

输出:

ACADEMY DINOSAUR|A Epic Drama of a Feminist And a Mad Scientist who must Battle a Teacher in The Canadian Rockies
ACE GOLDFINGER|A Astounding Epistle of a Database Administrator And a Explorer who must Find a Car in Ancient China

原站题解

SELECT f.title, f.description
FROM film f
JOIN film_category fc 
ON f.film_id = fc.film_id
JOIN category c 
ON c.category_id = fc.category_id
WHERE c.name = 'Action'

select f.title,f.description from film f left join film_category fc 
on f.film_id=fc.film_id where fc.category_id=(select category_id from category where name='Action')

select title ,description from film as f 
inner join film_category as fc on f.film_id = fc.film_id
where fc.category_id = (select category_id from category where name='Action');

select f.title, f.description
from film as f 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
where c.name = 'Action'

select f.title,f.description
from film f 
inner join  film_category fc 
on f.film_id=fc.film_id
where fc.category_id=(
    select category_id
    from category 
    where name="Action")