Redis数据类型－Set

Redis的set是string的无序集合。set元素最大可以包含2的32次方个元素

关于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，交集，差集。通过这些操作可以很容易的实现SNS中的好友推荐和BLOG的TAG功能。

sadd

添加元素

127.0.0.1:6379> sadd set value1
(integer) 1
127.0.0.1:6379> sadd set value1
(integer) 0

该条添加失败是因为已存在value1这个值了
127.0.0.1:6379> sadd set value2
(integer) 1
127.0.0.1:6379> smembers set
1) "value2"
2) "value1"

srem

删除元素

127.0.0.1:6379> smembers set
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> srem set value1
(integer) 1
127.0.0.1:6379> smembers set
1) "value3"
2) "value2"

spop

随机返回并删除一个元素

127.0.0.1:6379> smembers set
1) "value3"
2) "value2"
3) "value5"
4) "value4"
5) "value6"
127.0.0.1:6379> spop set
"value5"
127.0.0.1:6379> smembers set
1) "value4"
2) "value2"
3) "value3"
4) "value6"
127.0.0.1:6379> smembers set

sdiff

返回第一个和第二个差集

127.0.0.1:6379> smembers set1
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> smembers set2
1) "value2"
2) "value1"
127.0.0.1:6379> sdiff set1 set2
1) "value3"

sdiffstore

将set1与set2的差集存入set3中

127.0.0.1:6379> smembers set1
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> smembers set2
1) "value2"
2) "value1"
127.0.0.1:6379> sdiffstore set3 set1 set2
(integer) 1
127.0.0.1:6379> smembers set3
1) "value3"

sinter

得到所有KEY的交集，可以是2个也可以是多个

得到set1和set2的交集

127.0.0.1:6379> smembers set1
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> smembers set2
1) "value2"
2) "value1"
127.0.0.1:6379> sinter set1 set2
1) "value2"
2) "value1"

sinterstore

将指定的所有key的交集存入另一个集合中

如下：将set1和set2的交集存入store中

127.0.0.1:6379> smembers set1
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> smembers set2
1) "value2"
2) "value1"
127.0.0.1:6379> sinterstore store set1 set2
(integer) 2
127.0.0.1:6379> smembers store
1) "value1"
2) "value2"

sunion

得指定的所有KEY的并集

如下：得到 set1和set2的并集

127.0.0.1:6379> smembers set1
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> smembers set2
1) "value2"
2) "value1"
127.0.0.1:6379> sunion set1 set2
1) "value1"
2) "value2"
3) "value3"

sunionstore

将指定的所有KEY的并集存入另外一个集合中

如下：将set1和set2的并集存入store中

127.0.0.1:6379> smembers set1
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> smembers set2
1) "value2"
2) "value1"

127.0.0.1:6379> sunionstore store set1 set2
(integer) 3
127.0.0.1:6379> smembers store
1) "value1"
2) "value2"
3) "value3"

smove

将第一个集合的中value值移动到第二个集合中

如下:将set1的value3移动到set2中

127.0.0.1:6379> smembers set1
1) "value3"
2) "value2"
3) "value1"
127.0.0.1:6379> smembers set2
1) "value2"
2) "value1"
127.0.0.1:6379> smove set1 set2 'value3'
(integer) 1
127.0.0.1:6379> smembers set1
1) "value2"
2) "value1"
127.0.0.1:6379> smembers set2
1) "value3"
2) "value2"
3) "value1"

scard

返回一个集合中元素的个数

如下：得到set1中的元素个数

127.0.0.1:6379> smembers set1
1) "value2"
2) "value1"
127.0.0.1:6379> scard set1
(integer) 2

sismember

查看一个值是否存在一个集合中

127.0.0.1:6379> smembers set1
1) "value2"
2) "value1"
127.0.0.1:6379> sismember set1 'value1'
(integer) 1
127.0.0.1:6379> sismember set1 'value3'
(integer) 0

从上面可以看出，value1是set1中的，而value3不是set1中的

srandmember

随机得到一个集合中的值

127.0.0.1:6379> smembers set1
1) "value2"
2) "value1"

127.0.0.1:6379> srandmember set1
"value2"
127.0.0.1:6379> srandmember set1
"value2"
127.0.0.1:6379> srandmember set1
"value1"