Set是集合，它是string类型的无序集合。set是通过hash table实现的，添加删除和查找的负责度都是0（1）。对集合我们可以取并集，交集、差集。通过这些操作我们可以实现QQ和微博中的好友推荐和blog的tag功能。
sadd：向名称为key的set中添加元素
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127.0.0.1:6379> sadd myset1 one
(integer) 1
127.0.0.1:6379> sadd myset1 two
(integer) 1
127.0.0.1:6379> sadd myset1 two
(integer) 0
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smembers: 查看集合中的所有元素
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127.0.0.1:6379> smembers myset1
1)
"two"
2)
"one"
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srem：删除集合中的元素
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127.0.0.1:6379> sadd myset2
"one"
(integer) 1
127.0.0.1:6379> sadd myset2
"two"
(integer) 1
127.0.0.1:6379> srem myset2
"one"
(integer) 1
127.0.0.1:6379> smembers myset2
1)
"two"
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spop：随机返回并删除名称为key的set中的一个元素
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127.0.0.1:6379> smembers myset2
1)
"two"
2)
"three"
3)
"one"
127.0.0.1:6379> spop myset2
"two"
127.0.0.1:6379> smembers myset2
1)
"three"
2)
"one"
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sdiff：返回所有给定key与第一个key的差集
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127.0.0.1:6379> smembers myset3
1)
"two"
2)
"four"
3)
"three"
4)
"one"
127.0.0.1:6379> smembers myset2
1)
"three"
2)
"one"
127.0.0.1:6379>
sdiff
myset3 myset2
1)
"two"
2)
"four"
127.0.0.1:6379>
sdiff
myset2 myset3
(empty list or
set
)
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注意sdiff myset2 myset3 与 sdiff myset3 myset2的区别
sdiffstore：返回所有给定key与第一个key的差集，并将结果存为另一个key
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127.0.0.1:6379>
sdiff
myset3 myset2
1)
"two"
2)
"four"
127.0.0.1:6379> sdiffstore myset4 myset3 myset2
(integer) 2
127.0.0.1:6379> smembers myset4
1)
"two"
2)
"four"
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sinter：返回所有给定key的交集
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127.0.0.1:6379> smembers myset2
1)
"three"
2)
"one"
127.0.0.1:6379> smembers myset3
1)
"two"
2)
"four"
3)
"three"
4)
"one"
127.0.0.1:6379> sinter myset2 myset3
1)
"three"
2)
"one"
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sinterstore：返回所有给定key的交集，并将结果存为另一个key
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127.0.0.1:6379> smembers myset3
1)
"two"
2)
"four"
3)
"three"
4)
"one"
127.0.0.1:6379> sinter myset2 myset3
1)
"three"
2)
"one"
127.0.0.1:6379> sinterstore myset5 myset2 myset3
(integer) 2
127.0.0.1:6379> smembers myset5
1)
"three"
2)
"one"
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sunion：返回所有给定key的并集
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127.0.0.1:6379> smembers myset2
1)
"three"
2)
"one"
127.0.0.1:6379> smembers myset3
1)
"two"
2)
"four"
3)
"three"
4)
"one"
127.0.0.1:6379> sunion myset2 myset3
1)
"four"
2)
"three"
3)
"one"
4)
"two"
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suionstore：返回所有给定key的并集，并将结果存为另一个key
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127.0.0.1:6379> smembers myset2
1)
"three"
2)
"one"
127.0.0.1:6379> smembers myset3
1)
"two"
2)
"four"
3)
"three"
4)
"one"
127.0.0.1:6379> sunionstore myset6 myset2 myset3
(integer) 4
127.0.0.1:6379> smembers myset6
1)
"four"
2)
"three"
3)
"one"
4)
"two"
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smove：从第一个key对应的set中移除member并添加到第二个对应的set中
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127.0.0.1:6379> smembers myset3
1)
"two"
2)
"four"
3)
"three"
4)
"one"
127.0.0.1:6379> smembers myset2
1)
"three"
2)
"one"
127.0.0.1:6379> smove myset3 myset2 two
(integer) 1
127.0.0.1:6379> smembers myset2
1)
"two"
2)
"three"
3)
"one"
127.0.0.1:6379> smembers myset3
1)
"four"
2)
"three"
3)
"one"
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scard：返回名称为key的集合的元素个数
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127.0.0.1:6379> smembers myset3
1)
"four"
2)
"three"
3)
"one"
127.0.0.1:6379> scard myset3
(integer) 3
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sismember：测试member是否是名称为key的set的元素，如果是则返回1，否则返回0
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127.0.0.1:6379> smembers myset3
1)
"four"
2)
"three"
3)
"one"
127.0.0.1:6379> sismember myset3 one
(integer) 1
127.0.0.1:6379> sismember myset3 two
(integer) 0
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srandmember：随机返回名称为key的set的一个元素，但不删除元素
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srandmember key [count]
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127.0.0.1:6379> smembers myset3
1)
"four"
2)
"three"
3)
"one"
127.0.0.1:6379> srandmember myset3
"one"
127.0.0.1:6379> srandmember myset3
"four"
127.0.0.1:6379> srandmember myset3
"three"
127.0.0.1:6379> srandmember myset3
"one"
127.0.0.1:6379> srandmember myset3
"three"
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还可以传递count参数来一次随机获得多个元素。根据count值不同，意义也不相同
1、count为正数时，会随机从集合中获得count个不重复元素，如果count值大于集合元素的个数，则返回集合中所有元素
2、count为负数时，srandmember会随机从集合中返回|count|个元素，这些元素可能会重复
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127.0.0.1:6379> smembers myset3
1)
"four"
2)
"three"
3)
"one"
127.0.0.1:6379> srandmember myset3 5
1)
"three"
2)
"four"
3)
"one"
127.0.0.1:6379> srandmember myset3 2
1)
"four"
2)
"one"
127.0.0.1:6379> srandmember myset3 -2
1)
"four"
2)
"one"
127.0.0.1:6379> srandmember myset3 -2
1)
"one"
2)
"four"
127.0.0.1:6379> srandmember myset3 -2
1)
"one"
2)
"one"
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本文转自 曾哥最爱 51CTO博客，原文链接：http://blog.51cto.com/zengestudy/1859705，如需转载请自行联系原作者
