跟我学Redis（7）—set类型及操作

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set是集合，和我们数学中的集合概念相似，对集合的操作有添加删除元素，有对多个集合求交并差等操作，操作中key理解为集合的名字。

Redis的set是string类型的无序集合。set元素最大可以包含(2的32次方)个元素。 set的是通过hash table实现的，所以添加、删除和查找的复杂度都是O(1)。hash table 会随着添加或者删除自动的调整大小。

set 集合类型除了基本的添加删除操作，其他有用的操作还包含集合的取并集(union)，交集(intersection)，差集(difference)。

smembers

查看key对应的set的所有元素

语法：smembers key

sadd

向key对应的set中添加元素

语法：sadd key element

redis 127.0.0.1:6379> sadd myset2 "one" 
(integer) 1 
redis 127.0.0.1:6379> sadd myset2 "two" 
(integer) 1 
redis 127.0.0.1:6379> sadd myset2 "three" 
(integer) 1 
redis 127.0.0.1:6379> srem myset2 "one" 
(integer) 1 
redis 127.0.0.1:6379> srem myset2 "four" 
(integer) 0 
redis 127.0.0.1:6379> smembers myset2 1) "three" 
2) "two" 
redis 127.0.0.1:6379>

srem

删除key对应的set中的元素

语法：srem key element

redis 127.0.0.1:6379> srem myset2 "one" 
(integer) 1 
redis 127.0.0.1:6379> srem myset2 "four" 
(integer) 0 
redis 127.0.0.1:6379> smembers myset2 1) "three" 
2) "two" 
redis 127.0.0.1:6379>

spop

随机删除并返回key对应的set中一个元素

语法：spop key

redis 127.0.0.1:6379> spop myset3 "three" 
redis 127.0.0.1:6379> smembers myset3 1) "two" 
2) "one" 
redis 127.0.0.1:6379>

sdiff

set1和set2的差集（set1-set2）

语法：sdiff set1 set2

redis 127.0.0.1:6379>  smembers myset2 1) "three" 
2) "two" 
redis 127.0.0.1:6379>  smembers myset3 1) "two" 
2) "one" 
redis 127.0.0.1:6379> sdiff myset2 myset3 1) "three" 
redis 127.0.0.1:6379>

sdiffstore

差集并保存set3

语法：sdiffstore set3 set1 set2

redis 127.0.0.1:6379> smembers myset2 1) "three" 
2) "two" 
redis 127.0.0.1:6379> smembers myset3 1) "two" 
2) "one" 
redis 127.0.0.1:6379> sdiffstore myset4 myset2 myset3 (integer) 1 
redis 127.0.0.1:6379> smembers myset4 1) "three" 
redis 127.0.0.1:6379>

sinter

返回set1和set2的交集

语法：sinter set1 set2

redis 127.0.0.1:6379> smembers myset2 1) "three" 
2) "two" 
redis 127.0.0.1:6379> smembers myset3 1) "two" 
2) "one" 
redis 127.0.0.1:6379> sinter myset2 myset3 1) "two" 
redis 127.0.0.1:6379>

sinterstore

交集并保存到set3

语法：sinterstore set3 set1 set2

redis 127.0.0.1:6379> sinterstore myset5 myset2 myset3 (integer) 1 
redis 127.0.0.1:6379> smembers myset5 1) "two" 
redis 127.0.0.1:6379>

sunion

返回set1和set2的并集

语法：sunion set1 set2

redis 127.0.0.1:6379> sunion myset2 myset3 1) "three" 
2) "one" 
3) "two" 
redis 127.0.0.1:6379>

sunionstore

并集并保存到set3

语法：sunionstore set1 set2 set3

redis 127.0.0.1:6379> sunionstore myset6 myset2 myset3 (integer) 3 
redis 127.0.0.1:6379> smembers myset6 1) "three" 
2) "one" 
3) "two" 
redis 127.0.0.1:6379>

smove

从set1移动到set2

语法：smove set1 set2

redis 127.0.0.1:6379> smove myset2 myset7 three (integer) 1 
redis 127.0.0.1:6379> smembers myset7 1) "three" 
redis 127.0.0.1:6379>

scard

返回名称为key的set的元素个数

语法：scard key

redis 127.0.0.1:6379> scard myset2 (integer) 1 
redis 127.0.0.1:6379>

sismemeber

member是否是key对应set的元素

语法：sismember key element

redis 127.0.0.1:6379> smembers myset2 1) "two" 
redis 127.0.0.1:6379> sismember myset2 two (integer) 1 
redis 127.0.0.1:6379> sismember myset2 one (integer) 0 
redis 127.0.0.1:6379>

srangemember

随机返回key对应set的一个元素，但不删除

语法：srangemember key

redis 127.0.0.1:6379> smembers myset3 1) "two" 
2) "one" 
redis 127.0.0.1:6379> srandmember myset3 "two" 
redis 127.0.0.1:6379> srandmember myset3 "one" 
redis 127.0.0.1:6379>

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