sdiffstore

sdiffsotre(set different store 将两个集合的差集，保存到新的集合中,返回值是结果集元素的个数.

127.0.0.1:6379> smembers set1
1) "1"
2) "2"
3) "3"
127.0.0.1:6379> smembers set2
1) "1"
2) "2"
3) "3"
4) "4"
127.0.0.1:6379> sdiffstore destination set2 set1 
(integer) 1 这个1指的destination集合中有一个元素
127.0.0.1:6379> smembers destination
1) "4"
-----------------------------------------------------
127.0.0.1:6379> smembers set1
1) "1"
2) "2"
3) "3"
127.0.0.1:6379> smembers set2
1) "1"
2) "2"
3) "3"
4) "4"
127.0.0.1:6379> sdiffstore destination set1 set2
(integer) 0 这个0指的destination集合中有0个元素
127.0.0.1:6379> smembers destination
(empty list or set)