Store Set
Unlike the List type, duplicate elements are not allowed in the Set collection
The maximum number of elements a Set can contain is 4294967295
Common commands for storage set:
add/remove elements
get the elements in the collection
Difference operations in sets
Intersection operation in sets
Union operator in sets
extended command
sadd key member [member ...]
add set element
127.0.0.1:6379> sadd set1 a b c
(integer) 3
add three elements
smembers key
View the specified key set element
127.0.0.1:6379> smembers set1
1) "c"
2) "b"
3) "a"
127.0.0.1:6379> sadd set1 a d e
(integer) 2
127.0.0.1:6379> smembers set1
1) "c"
2) "d"
3) "b"
4) "a"
5) "e"
Continue to add elements and find that duplicate elements are no longer added
srem key member [member ...]
remove element
127.0.0.1:6379> srem set1 a d
(integer) 2
127.0.0.1:6379> smembers set1
1) "b"
2) "c"
3) "e"
delete two elements
sismember key member
To determine whether an element exists, return 1 to indicate that it exists and return 0 to indicate that it does not exist
127.0.0.1:6379> sismember set1 a
(integer) 0
127.0.0.1:6379> sismember set1 b
(integer) 1
sdiff calculates the difference
127.0.0.1:6379> sadd set2 a b c
(integer) 3
127.0.0.1:6379> sadd set3 b c d e
(integer) 4
127.0.0.1:6379> sdiff set2 set3
1) "a"
127.0.0.1:6379> sdiff set3 set2
1) "d"
2) "e"
我们发现 集合的顺序不同 结果不一样 根据前者参考
sinter计算交集
127.0.0.1:6379> sinter set2 set3
1) "c"
2) "b"
sunion计算并集
127.0.0.1:6379> sunion set2 set3
1) "e"
2) "a"
3) "b"
4) "c"
5) "d"
scard计算元素总数
127.0.0.1:6379> smembers set1
1) "b"
2) "c"
3) "e"
127.0.0.1:6379> scard set1
(integer) 3
srandmember 随机取一个元素
127.0.0.1:6379> srandmember set1
"c"
127.0.0.1:6379> srandmember set1
"e"
sdiffstore 把差集结果存储到新集合中
127.0.0.1:6379> smembers set2
1) "c"
2) "b"
3) "a"
127.0.0.1:6379> smembers set3
1) "c"
2) "e"
3) "d"
4) "b"
127.0.0.1:6379> sdiffstore r1 set2 set3
(integer) 1
127.0.0.1:6379> smembers r1
1) "a"
sinterstore 把交集结果存储到新集合中
127.0.0.1:6379> sinterstore r2 set2 set3
(integer) 2
127.0.0.1:6379> smembers r2
1) "c"
2) "b"
sunionstore把并集结果存储到新集合中
127.0.0.1:6379> sunionstore r3 set2 set3
(integer) 5
127.0.0.1:6379> smembers r3
1) "e"
2) "a"
3) "b"
4) "c"
5) "d"
存储Set使用场景
跟踪一些唯一性数据
用于维护数据对象之间的关联关系