sets

A Redis set is an unordered collection of unique strings (members).
无序的字符串集合

相关命令：

• SADD

SADD key member [member ...]

• SREM

SREM key member [member ...]

• SMEMBERS

Returns all the members of the set value stored at key.

• SISMEMBER

SISMEMBER key member

Returns if member is a member of the set stored at key.1 if the element is a member of the set.0 if the element is not a member of the set, or if key does not exist.

• SMISMEMBER

Returns whether each member is a member of the set stored at key.

SMISMEMBER key member [member ...]

• SINTER

  SINTER key [key ...]

  Returns the members of the set resulting from the intersection of all the given sets.求交集

• SCARD

Returns the set cardinality (number of elements) of the set stored at key.
计算集合中的基数，其实就是set中元素的总数量，因为set是没有重复的。

• SDIFF

SDIFF key [key ...]

Returns the members of the set resulting from the difference between the first set and all the successive sets.

返回第一个集合和剩余集合的差集，是指包含在第一个集合中但不包含在其他集合中的元素。

• SDIFFSTORE

SDIFFSTORE destination key [key ...]

This command is equal to SDIFF, but instead of returning the resulting set, it is stored in destination.

• SINTERCARD

This command is similar to SINTER, but instead of returning the result set, it returns just the cardinality of the result.

返回：结果交集中的元素数

• SINTERSTORE

This command is equal to SINTER, but instead of returning the resulting set, it is stored in destination.

• SMOVE

将 member 元素从 source 集合移动到 destination 集合

• SPOP

移除并返回集合中的一个随机元素

• SSCAN

Redis Sscan 命令用于迭代集合中键的元素。

SADD myset1 "hello"
SADD myset1 "hi"
SADD myset1 "bar"
sscan myset1 0 match h*

1) "0"
2) 1) "hello"
   2) "h1"

• SUNION
• SUNIONSTORE