redis集合

### redis文档
http://redisdoc.com/

### sadd
127.0.0.1:6379> sadd math1 1 2 3 4 5 
(integer) 5
127.0.0.1:6379> sadd math2 4 5 6 7 8 
(integer) 5
### srandmember
127.0.0.1:6379> srandmember math1 2
1) "5"
2) "4"
### sismember
127.0.0.1:6379> sismember math1 6
(integer) 0
### smembers
127.0.0.1:6379> smembers math1
1) "1"
2) "2"
3) "3"
4) "4"
5) "5"
### sinter
127.0.0.1:6379> sinter math1 math2
1) "4"
2) "5"
### sunion
127.0.0.1:6379> sunion math1 math2
1) "1"
2) "2"
3) "3"
4) "4"
5) "5"
6) "6"
7) "7"
8) "8"
### sdiff
127.0.0.1:6379> sdiff math1 math2
1) "1"
2) "2"
3) "3"
127.0.0.1:6379> sdiff math2 math1
1) "6"
2) "7"
3) "8"