set类型以及其操作

sets类型

sets类型以及操作
Set是无序集合，它是string类型的无序集合。set是通过hash table实现的，添加、删除和查找的复杂度都是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sns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，返回添加成功的个数

127.0.0.1:6379> sadd key member [member ...]
127.0.0.1:6379> sadd myset1 one
(integer) 1
127.0.0.1:6379> sadd myset1 two three
(integer) 2

smembers
查看集合元素

127.0.0.1:6379> smembers key
127.0.0.1:6379> smembers myset1
1) "one"
2) "two"
3) "three"

srem
删除名称为key的set中元素，返回成功执行的个数

127.0.0.1:6379> srem key member [member ...]
127.0.0.1:6379> srem myset1 one
(integer) 1
127.0.0.1:6379> smembers myset1
1) "two"
2) "three"

spop
随机返回并删除名称为key的set中的一个元素

spop key [count]
127.0.0.1:6379> spop myset1 2
1) "two"
2) "three"
127.0.0.1:6379> smembers myset1
(empty list or set)

sdiff
返回所有给定key与第一个key的差集
谁在前面以谁为标准，返回其他集合少于标准的

127.0.0.1:6379> sdiff key [key ...]
127.0.0.1:6379> smembers myset2
1) "two"
2) "four"
3) "three"
127.0.0.1:6379> smembers myset1
1) "one"
2) "two"
3) "three"
127.0.0.1:6379> sdiff myset1 myset2
1) "one"
127.0.0.1:6379> sdiff myset2 myset1
1) "four"

sdiffstore
返回两个集合的差集，并将差集存储到另一个集合里面

127.0.0.1:6379> sdiffstore destination key [key ...]
127.0.0.1:6379> sdiffstore myset3 myset1
(integer) 3
127.0.0.1:6379> smembers myset3
1) "one"
2) "two"
3) "three"
127.0.0.1:6379> sdiff myset4 myset1 myset2
(empty list or set)
127.0.0.1:6379> smembers myset1
1) "one"
2) "two"
3) "three"
127.0.0.1:6379> smembers myset2
1) "two"
2) "four"
3) "three"
127.0.0.1:6379> sdiffstore myset4 myset1 myset2
(integer) 1
127.0.0.1:6379> smembers myset4
1) "one"

sinter
返回所有给定key的交集

127.0.0.1:6379> sinter key [key ...]
127.0.0.1:6379> smembers myset1
1) "one"
2) "two"
3) "three"
127.0.0.1:6379> smembers myset2
1) "two"
2) "four"
3) "three"
127.0.0.1:6379> sinter myset1 myset2
1) "two"
2) "three"

sinterstore
返回两个集合的交集并且储存在指定集合内

127.0.0.1:6379> sinterstore destination key [key ...]
127.0.0.1:6379> sinterstore myset4 myset1 myset2
(integer) 2
127.0.0.1:6379> smembers myset4
1) "two"
2) "three"

sunion
返回所有给定集合的并集

127.0.0.1:6379> sunion key [key ...]
127.0.0.1:6379> smembers myset1
1) "one"
2) "two"
3) "three"
127.0.0.1:6379> smembers myset2
1) "two"
2) "four"
3) "three"
127.0.0.1:6379> sunion myset1 myset2
1) "one"
2) "two"
3) "four"
4) "three"

sunionstrore
返回给顶集合的并集，并且存储在另一个集合

127.0.0.1:6379> sunionstore destination key [key ...]
127.0.0.1:6379> sunionstore myset5 myset1 myset2
(integer) 4
127.0.0.1:6379> smembers myset5
1) "one"
2) "two"
3) "four"
4) "three"

smove
从个一的个key中的对应的set中移除member并添加到第二个对应的set中

127.0.0.1:6379> smove source destination member
127.0.0.1:6379> smembers myset1
1) "one"
2) "two"
127.0.0.1:6379> smembers myset2
1) "two"
2) "four"
3) "three"
127.0.0.1:6379> smove myset1 myset2 one
(integer) 1
127.0.0.1:6379> smembers myset1
1) "two"
127.0.0.1:6379> smembers myset2
1) "one"
2) "two"
3) "four"
4) "three"

scard
返回名称为key的集合中的集合的个数

127.0.0.1:6379> scard key
127.0.0.1:6379> scard myset1
(integer) 1
127.0.0.1:6379> scard myset2
(integer) 4

sismember
测试某个元素是不是某个集合的元素

127.0.0.1:6379> sismember key member
127.0.0.1:6379> sismember myset1 one
(integer) 0
127.0.0.1:6379> sismember myset two
(integer) 0
127.0.0.1:6379> smembers myset1
1) "two"
127.0.0.1:6379> sismember myset1 two
(integer) 1

srandmember
随机返回集合中的一个元素，但不删除

127.0.0.1:6379> srandmember key [count]
127.0.0.1:6379> srandmember myset2
"four"
127.0.0.1:6379> srandmember myset2
"one"
127.0.0.1:6379> srandmember myset2 6
1) "one"
2) "two"
3) "three"
4) "four"