mysql使用技巧之行类视图子查询

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);

SELECT c.name, COUNT(f.film_id) AS amount
FROM film AS f, film_category AS fc, category AS c,
(SELECT category_id FROM film_category GROUP BY category_id HAVING COUNT(category_id) >= 5) AS cc
WHERE f.description LIKE '%robot%'
AND f.film_id = fc.film_id
AND fc.category_id = c.category_id
AND c.category_id = cc.category_id