比如在MySQL里面，对内容的标签有以下简单的几张表，我这里只列出来拆分过后的表结构

内容表：
CREATE TABLE `content` (
 `id` int(10) unsigned NOT NULL, -- 内容ID，唯一。
 `name` varchar(60) DEFAULT NULL, -- 内容的名字
 `created_timestamp` timestamp NULL DEFAULT NULL, -- 内容的加入时间
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1


标签表：
CREATE TABLE `tag` (
 `tag_name` varchar(60) NOT NULL, -- 标签名字，唯一
 `visit_count` int(10) unsigned NOT NULL DEFAULT '0', -- 标签的访问次数
 PRIMARY KEY (`tag_name`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1


内容与标签的关系，多对多。


CREATE TABLE `content_tag_relation` (
 `content_id` int(10) unsigned NOT NULL, -- 内容ID
 `tag_name` varchar(60) NOT NULL -- 标签名字
) ENGINE=InnoDB DEFAULT CHARSET=latin1

SELECT a.name FROM content AS a,content_tag_relation AS b
WHERE a.id = b.content_id AND b.tag_name = 'mysql'

SELECT tag_name FROM tag WHERE 1 ORDER BY visit_count DESC LIMIT 3;

	t_girl:6379> set string:content_id:4 '{"name":"test48601","created_timestamp":"2012-01-01 05:41:01"}'
	OK
	t_girl:6379> get string:content_id:4
	"{\"name\":\"test48601\",\"created_timestamp\":\"2012-01-01 05:41:01\"}"

	t_girl:6379> hset 'hset:content_id:4' name 'test48601'
	(integer) 1
	t_girl:6379> hset 'hset:content_id:4' created_timestamp '2012-01-01 05:41:01'
	(integer) 1

	t_girl:6379> hget hset:content_id:4 name
	"test48601"
	t_girl:6379> hget hset:content_id:4 created_timestamp
	"2012-01-01 05:41:01"
	t_girl:6379> 

	t_girl:6379> zadd zset:tag 680 database 469 db2
	(integer) 2

	t_girl:6379> zrevrangebyscore zset:tag +inf 0 limit 0 3
	1) "mongodb"
	2) "sql"
	3) "postgresql"

	t_girl:6379> sadd set:content_id:4 role mongodb role database 
	(integer) 3

	t_girl:6379> smembers set:content_id:4
	1) "database"
	2) "role"
	3) "mongodb"

 import redis
	 content_id_keys = r.keys('set*')
	 content_id_keys_len = len(content_id_keys)
	
	 i = 0
	 j = 0
	 content_name_list = []
	 while i < content_id_keys_len:
	 if r.sismember(content_id_keys[i],'mysql') == 1:
	 content_name_list.append(eval(r.get(content_id_keys[i].replace('set','string')))['name'])
	 print('Content name is :' + content_name_list[j])
	 j += 1
	 i += 1 

	t_girl:6379> sadd tag:mysql test123 test133 test144 test155
	(integer) 4
	t_girl:6379> smembers tag:mysql
	1) "test133"
	2) "test155"
	3) "test123"
	4) "test144"