原文

http://redis.io/commands/sdiff

简介

Subtract multiple sets.

多个集合的差集。

语法

SDIFF key [key ...]

版本

Available since 1.0.0.

自1.0.0版本可用。

时间复杂度

Time complexity: O(N) where N is the total number of elements in all given sets.

O(N)：N是所有给定集合中元素的总数。

描述

Returns the members of the set resulting from the difference between the first set and all the successive sets.

返回在第一个集合中存在，但是在后面的集合中都不存在的元素。

For example:

key1 = {a,b,c,d}
key2 = {c}
key3 = {a,c,e}
SDIFF key1 key2 key3 = {b,d}

Keys that do not exist are considered to be empty sets.

不存在的key被认为是空集合。

返回值

Array reply: list with members of the resulting set.

Array：结果集合的成员列表。

例子

redis>  SADD key1 "a"
(integer) 1
redis>  SADD key1 "b"
(integer) 1
redis>  SADD key1 "c"
(integer) 1
redis>  SADD key2 "c"
(integer) 1
redis>  SADD key2 "d"
(integer) 1
redis>  SADD key2 "e"
(integer) 1
redis>  SDIFF key1 key2
1) "b"
2) "a"
redis>