sdiff
sdiff(set different) 返回两个集合之间的差集
127.0.0.1:6379> smembers connections 1) "user:2" 2) "user:1" 3) "user:3" 127.0.0.1:6379> smembers friends 1) "user:2" 2) "user:1" # sdiff connections friends:集合connections有那些元素,是在集合friends中没有的 127.0.0.1:6379> sdiff connections friends 1) "user:3" ------------------------------------------ 127.0.0.1:6379> smembers set1 1) "1" 2) "2" 3) "3" 4) "4" 127.0.0.1:6379> smembers set2 1) "1" 2) "2" 3) "3" # sdiff set1 set2:在set1中有那些元素是在set2中没有的 127.0.0.1:6379> sdiff set1 set2 1) "4" 在set1中4这个元素,是在set2中没有的 127.0.0.1:6379> sdiff set2 set1 (empty list or set) set2中元素,set1都有,所以返回为空