Set类型是一个没有排序的集合，可以在该类型那个执行添加、删除或判断某一元素是否存在等操作。由于Redis的内部是使用值为空的hash table实现的，所以操作的时间复杂度为O(1), 最多存储2^32-1个字符串。
Set集合中不允许出现重复的元素，和List类型相比，Set类型在功能上另一个优势是可以进行并集，交集，差集运算。
sadd
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129.223.248.154:6379> sadd students tim
(integer) 1
129.223.248.154:6379> sadd students tim ben
(integer) 1
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srem
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129.223.248.154:6379> srem student tim
(integer) 0
129.223.248.154:6379> srem students tim
(integer) 1
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smembers、sismember
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129.223.248.154:6379> smembers students
1)
"ben"
129.223.248.154:6379> sismember students ben
(integer) 1
129.223.248.154:6379> sismember students tim
(integer) 0
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sdiff 差集
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8
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129.223.248.154:6379> sadd setDiffA 1 2 3
(integer) 3
129.223.248.154:6379> sadd setDiffB 2 3 4
(integer) 3
129.223.248.154:6379>
sdiff
setDiffA setDiffB
1)
"1"
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sinter 交集
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129.223.248.154:6379> sadd setInterA 1 2 3
(integer) 3
129.223.248.154:6379> sadd setInterB 2 3 4
(integer) 3
129.223.248.154:6379>
sinter
setInterA setInterB
1)
"2"
2)
"3"
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sunion 并集
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129.223.248.154:6379> sadd setUnionA 1 2 3
(integer) 3
129.223.248.154:6379> sadd setUnionB 2 4 6
(integer) 3
129.223.248.154:6379>
sunion
setUnionA setUnionB
1)
"1"
2)
"2"
3)
"3"
4)
"4"
5)
"6"
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scard 集合总数
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129.223.248.154:6379>
scard
students
(integer) 1
129.223.248.154:6379> smembers students
1)
"ben"
129.223.248.154:6379> srandmember students
"ben"
129.223.248.154:6379> sadd students mike
(integer) 1
129.223.248.154:6379> srandmember students
"ben"
129.223.248.154:6379> srandmember students
"mike"
129.223.248.154:6379> srandmember students
"mike"
129.223.248.154:6379> sadd memebrs a b c
(integer) 3
129.223.248.154:6379> srandmember students 2
1)
"ben"
2)
"mike"
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srandmember
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7
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129.223.248.154:6379> sadd letters a b c
(integer) 3
129.223.248.154:6379>
srandmember
letters 2
1)
"b"
2)
"c"
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spop
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129.223.248.154:6379> spop letters
"b"
129.223.248.154:6379> smembers letters
1)
"a"
2)
"c"
129.223.248.154:6379>
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本文转自 yuanzhitang 51CTO博客，原文链接：http://blog.51cto.com/yuanzhitang/1789613，如需转载请自行联系原作者
