redis--sets类型及操作

心已赠人 2022-07-16 01:11 204阅读 0赞

# sets类型 #

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

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 three
    (integer) 1
    127.0.0.1:6379> sadd myset1 three
    (integer) 0
    127.0.0.1:6379> smembers myset1
    1) "two"
    2) "one"
    3) "three"

注：集合里面不允许有重复的值。

# srem #

删除名称为key的set中的元素

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

# spop #

随机返回并删除名称为key的set中一个元素

127.0.0.1:6379> sadd myset3 one
    (integer) 1
    127.0.0.1:6379> sadd myset3 two
    (integer) 1
    127.0.0.1:6379> sadd myset3 three
    (integer) 1
    127.0.0.1:6379> sadd myset3 four
    (integer) 1
    127.0.0.1:6379> sadd myset3 five
    (integer) 1
    127.0.0.1:6379> smembers myset3
    1) "two"
    2) "one"
    3) "four"
    4) "three"
    5) "five"
    127.0.0.1:6379> spop myset3
    "one"
    127.0.0.1:6379> spop myset3
    "two"
    127.0.0.1:6379> spop myset3
    "five"
    127.0.0.1:6379> smembers myset3
    1) "four"
    2) "three"

# sdiff #

返回给定集合的差集

127.0.0.1:6379> smembers myset1
    1) "two"
    2) "one"
    127.0.0.1:6379> smembers myset2
    1) "one"
    2) "three"
    127.0.0.1:6379> sdiff myset1 myset2
    1) "two"
    127.0.0.1:6379> sdiff myset2 myset1
    1) "three"

注：sdiff myset1 myset2 谁在前面以谁为标准

# sdiffstore #

将给定集合差集存储到另一个集合

127.0.0.1:6379> sdiff myset2 myset1
    1) "three"
    127.0.0.1:6379> sdiffstore myset5 myset2 myset1
    (integer) 1
    127.0.0.1:6379> smembers myset5
    1) "three"

# sinter #

返回所有给定的key的交集

127.0.0.1:6379> smembers myset1
    1) "two"
    2) "one"
    127.0.0.1:6379> smembers myset2
    1) "one"
    2) "three"
    127.0.0.1:6379> sinter myset1 myset2
    1) "one"

# sinterstore #

返回所有给定的key的交集，并将结果存放为另一个key

127.0.0.1:6379> smembers myset2
    1) "one"
    2) "three"
    127.0.0.1:6379> smembers myset3
    1) "four"
    2) "three"
    127.0.0.1:6379> sinter myset1 myset2
    1) "one"
    127.0.0.1:6379> sinterstore myset6  myset1 myset2
    (integer) 1
    127.0.0.1:6379> smembers myset6
    1) "one"

# sunion #

返回所有给定集合的并集

127.0.0.1:6379> smembers myset1
    1) "two"
    2) "one"
    127.0.0.1:6379> smembers myset2
    1) "one"
    2) "three"
    127.0.0.1:6379> sunion myset1 myset2
    1) "one"
    2) "two"
    3) "three"

# sunionstore #

将给定集合的并集存储到另一个集合

127.0.0.1:6379> smembers myset1
    1) "two"
    2) "one"
    127.0.0.1:6379> smembers myset2
    1) "one"
    2) "three"
    127.0.0.1:6379> sunion myset1 myset2
    1) "one"
    2) "two"
    3) "three"
    127.0.0.1:6379> sunionstore myset7 myset1 myset2
    (integer) 3
    127.0.0.1:6379> smembers myset7
    1) "one"
    2) "two"
    3) "three"

# smove #

从第一个集合中移出某一个元素，并放到第二个集合中。

127.0.0.1:6379> smembers myset1
    1) "two"
    2) "one"
    127.0.0.1:6379> smembers myset2
    1) "one"
    2) "three"
    127.0.0.1:6379> smove myset1 myset2 two
    (integer) 1
    127.0.0.1:6379> smembers myset1
    1) "one"
    127.0.0.1:6379> smembers myset2
    1) "two"
    2) "one"
    3) "three"

# scard #

返回名称为key的set的元素个数

127.0.0.1:6379> smembers myset2
    1) "two"
    2) "one"
    3) "three"
    127.0.0.1:6379> scard myset2
    (integer) 3

# sismember #

判断一个值是否为一个集合的元素

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

返回1则代表是，返回0则代表不是。

# srandmember #

随机返回一个集合中的某个元素但不删除这个元素

127.0.0.1:6379> smembers myset2
    1) "two"
    2) "one"
    3) "three"
    127.0.0.1:6379> srandmember myset2
    "three"
    127.0.0.1:6379> srandmember myset2
    "one"
    127.0.0.1:6379> srandmember myset2
    "two"
    127.0.0.1:6379> srandmember myset2
    "three"
    127.0.0.1:6379> srandmember myset2
    "three"

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注：set类型是无序集合，即集合中的所有元素都没有顺序。还有另一种sorted sets类型是set的一个升级版本，它在set的基础上增加了一个顺序属性。