set集合類型的操作（無序集合）——redis
1. set集合類型的操作（無序集合）
集合具有無序性（沒有順序）、確定性（描述是確定的）、唯一性（沒有重復的元素）
1.1. sadd key member [member ...]
語法：sadd key member [member ...]
作用：往集合key中添加元素
返回值：添加元素的個數
例：
127.0.0.1:6379> sadd fruit apple banana pear
(integer) 3
127.0.0.1:6379> sadd num 1 1
(integer) 1
1.2. smembers key
語法：smembers key
作用：返回集合
例：
127.0.0.1:6379> smembers fruit
1) "pear"
2) "banana"
3) "apple"
127.0.0.1:6379> smembers num
1) "1"
1.3. srandmember key [count]
語法：srandmember key [count]
作用：返回集合key中隨機的1個元素
例：
127.0.0.1:6379> smembers letter
1) "d"
2) "g"
3) "c"
4) "e"
5) "a"
127.0.0.1:6379> srandmember letter
"e"
127.0.0.1:6379> srandmember letter
"c"
127.0.0.1:6379> srandmember letter
"a"
127.0.0.1:6379> srandmember letter 2
1) "c"
2) "e"
127.0.0.1:6379> srandmember letter 3
1) "c"
2) "e"
3) "a"
127.0.0.1:6379> smembers letter
1) "d"
2) "g"
3) "c"
4) "e"
5) "a"
1.4. srem key member [member ...]
語法：
作用：刪除集合key中的member [member...]元素
返回值：忽略不存在的元素後，真正刪除掉的元素的個數
例：
127.0.0.1:6379> smembers num
1) "1"
127.0.0.1:6379> srem num 1
(integer) 1
127.0.0.1:6379> smembers num
(empty list or set)
127.0.0.1:6379> srem fruit pear
(integer) 1
127.0.0.1:6379> smembers fruit
1) "banana"
2) "apple"
1.5. spop key [count]
語法：spop key [count]
作用：返回並刪除集合key中1個隨機的元素
例：
127.0.0.1:6379> sadd letter a b c d e f g
(integer) 7
127.0.0.1:6379> smembers letter
1) "c"
2) "d"
3) "g"
4) "b"
5) "e"
6) "a"
7) "f"
127.0.0.1:6379> spop letter
"b"
127.0.0.1:6379> smembers letter
1) "d"
2) "g"
3) "c"
4) "e"
5) "a"
6) "f"
127.0.0.1:6379> spop letter
"f"
127.0.0.1:6379> smembers letter
1) "d"
2) "g"
3) "c"
4) "e"
5) "a"
案例：
spop是返回並刪除一個隨機的元素，所以可以用來做抽獎，第一次spop出的可以作為第一名（一等獎），第二次spop出的可以作為第二名（二等獎）...
1.6. sismember key member
語法：sismember key member
作用：判斷member是否是集合key中的元素
返回值：是返回1；不是返回0
例：
127.0.0.1:6379> smembers letter
1) "d"
2) "g"
3) "c"
4) "e"
5) "a"
127.0.0.1:6379> sismember letter a
(integer) 1
127.0.0.1:6379> sismember letter k
(integer) 0
127.0.0.1:6379> sismember letter 0
(integer) 0
1.7. scard key
語法：scard key
作用：返回集合key中元素的個數
例：
127.0.0.1:6379> smembers letter
1) "d"
2) "g"
3) "c"
4) "e"
5) "a"
127.0.0.1:6379> scard letter
(integer) 5
1.8. sinter key [key ...]
語法：sinter key [key ...]
作用：求出key [key ...]幾個集合中的交集，並返回
例：
127.0.0.1:6379> sadd lisa c python java
(integer) 3
127.0.0.1:6379> sadd wang english python php
(integer) 3
127.0.0.1:6379> sadd poly python redis c++
(integer) 3
127.0.0.1:6379> sinter lisa wang poly
1) "python"
127.0.0.1:6379> sadd tom python java php redis
(integer) 4
127.0.0.1:6379> sinter tom poly
1) "redis"
2) "python"
1.9. sinterstore destination key [key ...]
語法：sinterstore destination key [key ...]
作用：求出key [key ...]幾個集合中的交集，並賦給destination或存儲在destination中
返回值：返回真正存儲到destination中的元素的個數
例：
127.0.0.1:6379> smembers lisa
1) "python"
2) "java"
3) "c"
127.0.0.1:6379> smembers poly
1) "c++"
2) "redis"
3) "python"
127.0.0.1:6379> smembers tom
1) "redis"
2) "php"
3) "python"
4) "java"
127.0.0.1:6379> sinterstore lisa_tom lisa tom
(integer) 2
127.0.0.1:6379> smembers lisa_tom
1) "python"
2) "java"
1.10. sunion key [key ...]
語法：sunion key [key ...]
作用：求出key [key ...]幾個集合的並集，並返回
例：
127.0.0.1:6379> sadd lisa c python java
(integer) 3
127.0.0.1:6379> sadd wang english python php
(integer) 3
127.0.0.1:6379> sadd poly python redis c++
(integer) 3
127.0.0.1:6379> sunion lisa wang
1) "python"
2) "c"
3) "java"
4) "php"
5) "english"
127.0.0.1:6379> sadd tom python java php redis
(integer) 4
127.0.0.1:6379> sunion lisa wang tom poly
1) "php"
2) "c"
3) "c++"
4) "redis"
5) "python"
6) "english"
7) "java"
1.11. sdiff key [key ...]
語法：sdiff key [key ...]
作用：求出key與[key ...]的差集
例：
127.0.0.1:6379> smembers lisa
1) "python"
2) "java"
3) "c"
127.0.0.1:6379> smembers tom
1) "redis"
2) "php"
3) "python"
4) "java"
127.0.0.1:6379> sdiff lisa tom
1) "c"
127.0.0.1:6379> sdiff tom lisa
1) "redis"
2) "php"
127.0.0.1:6379> smembers poly
1) "c++"
2) "redis"
3) "python"
127.0.0.1:6379> sdiff tom lisa poly
1) "php"
set集合類型的操作（無序集合）——redis