Redis5数据类型4-Set集合

1. Set集合介绍

Set数据有几个特点：

• 无序的、去重的
• 元素是字符串类型
• 最多包含2³²-1个元素

2. Set指令

2.1 增加一个或多个元素

sadd key member [member ...]

127.0.0.1:6379> sadd friends hanmeimei
1
127.0.0.1:6379> sadd friends lilei piter poly
3
127.0.0.1:6379> sadd friends lucy lilei
1
127.0.0.1:6379> sadd friends lilei
0
127.0.0.1:6379>

2.2 查看所有元素

smembers key

127.0.0.1:6379> smembers friends
hanmeimei
piter
poly
lucy
lilei
127.0.0.1:6379> smembers friends
hanmeimei
piter
poly
lucy
lilei
127.0.0.1:6379>

注意：虽然是无序的，但是数据少，可能要进行大量测试才能看出

2.3 返回集合中元素的个数

scard key

127.0.0.1:6379> scard friends
5
127.0.0.1:6379>

2.4 移除一个或者多个元素

srem key member [member ...]

127.0.0.1:6379> sadd friends a b c d
4
127.0.0.1:6379> smembers friends
hanmeimei
piter
poly
c
b
a
lucy
lilei
d
127.0.0.1:6379> srem friends a
1
127.0.0.1:6379> smembers friends
piter
poly
c
b
lucy
lilei
hanmeimei
d
127.0.0.1:6379> srem friends b c d
3
127.0.0.1:6379> smembers friends
lilei
hanmeimei
poly
piter
lucy
127.0.0.1:6379>

2.5 检查元素是否存在集合中

sismember key member

127.0.0.1:6379> sismember friends lucy
1
127.0.0.1:6379> sismember friends a
0
127.0.0.1:6379>

2.6 随机返回集合中指定个数的元素

srandmember key [count]

• count 不指定，随机返回一个元素
• count = 0，返回空
• count > 0，若count小于集合中元素的个数，那么命令返回一个包含 count 个元素的数组，数组中的元素各不相同。若 count 大于等于集合中元素的个数，那么返回整个集合
• count < 0，返回长度为count绝对值长度的数组，数据中的元素可能会重复

127.0.0.1:6379> srandmember friends
poly
127.0.0.1:6379> srandmember friends 0

127.0.0.1:6379> srandmember friends 3
hanmeimei
piter
lucy
127.0.0.1:6379> srandmember friends 10
lilei
hanmeimei
poly
piter
lucy
127.0.0.1:6379> srandmember friends -3
piter
poly
poly
127.0.0.1:6379>

用处：适合抽奖

2.7 随机移除一个元素并返回此元素

spop key

127.0.0.1:6379> spop friends
lucy
127.0.0.1:6379> smembers friends
lilei
hanmeimei
poly
piter
127.0.0.1:6379>

2.8 把元素从源集合移动到目标集合

smove key dest member

127.0.0.1:6379> smove friends fs piter
1
127.0.0.1:6379> smembers friends
lilei
hanmeimei
poly
127.0.0.1:6379> smembers fs
piter
127.0.0.1:6379>

2.9 差集

• sdiff key [key ...]
  差集，具有方向性
• sdiffstore destination key [key ...] 将差集结果存储在目标key中

127.0.0.1:6379> sadd no1 1 2 3 4 5
5
127.0.0.1:6379> sadd no2 4 5 6 7 8
5
127.0.0.1:6379> sdiff no1 no2
1
2
3
127.0.0.1:6379> sdiff no2 no1
6
7
8
127.0.0.1:6379> sdiffstore no3 no1 no2
3
127.0.0.1:6379> smembers no3
1
2
3
127.0.0.1:6379>

2.10 交集

• sinter key [key ...]
• sinterstore destination key [key ...] 将交集结果存储在目标key中

127.0.0.1:6379> sinter no1 no2
4
5
127.0.0.1:6379> sinterstore no4 no1 no2
2
127.0.0.1:6379> smembers no4
4
5
127.0.0.1:6379>

用处：使用交集，可以统计2个账户的共同好友或者共同关注的人

2.11 并集

• sunion key [key ...]
• sunionstore destination key [key ...] 将并集结果存储在目标key中

127.0.0.1:6379> sunion no1 no2
1
2
3
4
5
6
7
8
127.0.0.1:6379> sunionstore no5 no1 no2
8
127.0.0.1:6379> smembers no5
1
2
3
4
5
6
7
8
127.0.0.1:6379>