Redis 的 Set 是 String 類型的無序集合。集合成員是唯一的，這就意味著集合中不能出現重復的數據。
Redis 中集合是通過哈希表實現的，所以添加，刪除，查找的復雜度都是 O(1)。
集合中最大的成員數為 232 - 1 (4294967295, 每個集合可存儲40多億個成員)。
實例：
redis 127.0.0.1:6379> SADD runoobkey redis
(integer) 1
redis 127.0.0.1:6379> SADD runoobkey mongodb
(integer) 1
redis 127.0.0.1:6379> SADD runoobkey mysql
(integer) 1
redis 127.0.0.1:6379> SADD runoobkey mysql
(integer) 0
redis 127.0.0.1:6379> SMEMBERS runoobkey1) "mysql"
2) "mongodb"
3) "redis"
1、Set常用命令
1.1、SADD
127.0.0.1:6379> sadd myset "hello" //set集合添加元素
(integer) 1
127.0.0.1:6379> sadd myset "lizhengi"
(integer) 1
127.0.0.1:6379> sadd myset "world"
(integer) 1
127.0.0.1:6379> SMEMBERS myset //查看指定set所有值
1) "world"
2) "lizhengi"
3) "hello"
127.0.0.1:6379> SISMEMBER myset hello //判斷某個值是否在set中
(integer) 1
127.0.0.1:6379> SISMEMBER myset hh
(integer) 01.2、scard
127.0.0.1:6379> scard myset //獲取set長度
(integer) 3
1.3、srem
127.0.0.1:6379> SMEMBERS myset
1) "world"
2) "lizhengi"
3) "hello"
127.0.0.1:6379> srem myset hello world //移除set集合中指定一些元素
(integer) 2
127.0.0.1:6379> scard myset
(integer) 1
127.0.0.1:6379> SMEMBERS myset
1) "lizhengi"
127.0.0.1:6379>
1.4、SRANDMEMBER
127.0.0.1:6379> SRANDMEMBER myset //隨機抽出set集合的一個元素
"hello"
127.0.0.1:6379> SRANDMEMBER myset
"world"
127.0.0.1:6379>
1.5、SPOP
127.0.0.1:6379> SMEMBERS myset
1) "adsa"
2) "world"
3) "lizhengi"
4) "hello"
127.0.0.1:6379> SPOP myset //隨機刪除set集合某些元素
"lizhengi"
127.0.0.1:6379> SPOP myset
"hello"
127.0.0.1:6379> SMEMBERS myset
1) "adsa"
2) "world"
127.0.0.1:6379>
1.6、SMOVE
127.0.0.1:6379> SMEMBERS myset
1) "adsa"
2) "world"
127.0.0.1:6379> sadd myset2 "adsa"
(integer) 1
127.0.0.1:6379> SMEMBERS myset
1) "adsa"
2) "world"
127.0.0.1:6379> SMEMBERS myset2
1) "adsa"
127.0.0.1:6379> SMOVE myset myset2 "world" //移動指定元素到另外一個集合
(integer) 1
127.0.0.1:6379> SMEMBERS myset
1) "adsa"
127.0.0.1:6379> SMEMBERS myset2
1) "adsa"
2) "world"
127.0.0.1:6379> 1.7、SDIFF 、SINTER、SUNION
127.0.0.1:6379> SMEMBERS myset
1) "adsa"
2) "aadsa"
127.0.0.1:6379> SMEMBERS myset2
1) "adsa"
2) "world"
127.0.0.1:6379> SDIFF myset myset2 //差集
1) "aadsa"
127.0.0.1:6379> SINTER myset myset2 //交集
1) "adsa"
127.0.0.1:6379> SUNION myset myset2 //并集
1) "adsa"
2) "world"
3) "aadsa"
