如何在Redis中建立多对多关系

使用Redis，关系通常由集合表示。一组可用于表示单向关系，因此每个对象需要一组以表示多对多关系。

尝试将关系数据库模型与Redis数据结构进行比较是毫无用处的。使用Redis，所有内容均以非规范化方式存储。

例：

# Here are my categories> hmset category:1 name cinema  ... more fields ...> hmset category:2 name music   ... more fields ...> hmset category:3 name sports  ... more fields ...> hmset category:4 name nature  ... more fields ...# Here are my users> hmset user:1 name Jack   ... more fields ...> hmset user:2 name John   ... more fields ...> hmset user:3 name Julia  ... more fields ...# Let's establish the many-to-many relationship# Jack likes cinema and sports# John likes music and nature# Julia likes cinema, music and nature# For each category, we keep a set of reference on the users> sadd category:1:users 1 3> sadd category:2:users 2 3> sadd category:3:users 1> sadd category:4:users 2 3# For each user, we keep a set of reference on the categories> sadd user:1:categories 1 3> sadd user:2:categories 2 4> sadd user:3:categories 1 2 4

一旦有了此数据结构，就可以使用集合代数查询它：

# Categories of Julia> smembers user:3:categories1) "1"2) "2"3) "4"# Users interested by music> smembers category:2:users1) "2"2) "3"# Users interested by both music and cinema> sinter category:1:users category:2:users1) "3"