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:categories
1) "1"
2) "2"
3) "4"

# Users interested by music
> smembers category:2:users
1) "2"
2) "3"

# Users interested by both music and cinema
> sinter category:1:users category:2:users
1) "3"