sadd key member1 member2 scard key 获取集合元素个数 sdiff key1 key2 差集 key1-key2的差集   sdiff key1 key2 不等于 sdiff key2 key1  sdiffstore newkey ke1 key2  key1 - key2的差集，且保存到newkey中 smembers key 展示所有的元素 sismember key member 判断元素是否在key中 sinter key1 key2 交集 sinterstore newkey key1 key2 spop key 随机移除一个元素 srem key member 移除一个或者多个元素 sunion key1 key2 返回并集 sunionstore newkey key1 key2  并集存储到newkey smove sourcekey desckey member 将member移到desckey sscan key  cursor  match pattern