For data in Redis, it is generally a key-value pair, and different data types refer to the type of value in the key-value pair .
About key
| command | effect |
|---|---|
| DEL key | This command is used to delete the key when the key exists |
| EXISTS key | Check if the given key exists |
| MOVE key db | Move the key of the current database to the given database db |
| TYPE key | Returns the type of the value stored in the key |
| SET key value | Set up a kv key-value pair |
1.String：Redis中最基本的类型，它是key对应的一个单一值。二进制安全，不必担心由于编码等问题导致二进制数据变化。所以redis的string可以包含任何数据，比如jpg图片或者序列化的对象。Redis中一个字符串值的最大容量是512M。
| command | effect |
|---|---|
| GET key | Get the value according to the key |
| STRLEN key | Returns the length of the string value stored in key |
| INCR key | Increment the numeric value stored in the key by 1 |
| INCRBY key increment | Add the value stored in the key to the given increment (increment) |
| MSET KEY VALUE [KEY VALUE …] | Set up a group of multiple key-value pairs at once |
| MGET KEY [KEY …] | Specify multiple KEYs at once and return their corresponding values. The return value of KEYs without values is (nil) |
2.List:Redis 列表是简单的字符串列表，按照插入顺序排序。可以添加一个元素到列表的头部（左边）或者尾部（右边）。说明它的底层是基于链表实现的，所以它操作时头尾效率高，中间效率低
| command | effect |
|---|---|
| LPUSH key value [value …] | Add data from the left |
| RPUSH key value [value …] | Add data from the right |
| LRANGE key start stop | Print the list collection according to the index (0 -1 range is all data) |
| FILL key | the length of the list collection |
| LPOP key | Move out and get the first element of the list |
| RPOP key | Remove the last element of the list, and the return value is the removed element. |
| LINDEX key index | Get a value from the collection based on the index |
| LSET key index value | Only keep the data in the specified interval, the data on both sides are deleted |
| LTRIM key start stop | Only keep the data in the specified interval, the data on both sides are deleted |
3.Set: Redis 的 Set 是 String 类型的无序集合。集合成员是唯一的，这就意味着集合中不能出现重复的数据。Redis 中集合是通过哈希表实现的，所以添加，删除，查找的复杂度都是 O(1) 。
| command | effect |
|---|---|
| SADD key member [member …] | Add one or more members to the collection (not repeatable) |
| SCARD key | Get the number of members in the collection |
| SMEMBERS key | View all data in the set collection |
| SREM key member1 [member2] | Remove one or more members from the collection |
| SUNION key1 [key2] | Returns the union of all given sets |
4.Hash：Redis hash 是一个 string 类型的 field（字段） 和 value（值） 的映射表，hash 特别适合用于存储对象,hash数据类型可以理解为java中的Map<String,String>
| project | Value |
|---|---|
| HSET key field value | adding data |
| HGETALL key | Query all data of a key |
| HGET key field | Query the data of a key corresponding to the field |
| HKEYS key | Get all fields in the hash table |
| HLEN key | Get the number of fields in the hash table |
| WHALE key | Get all the values in the hash table |
| HEXISTS key field | Determine whether the specified field exists in a key |
| HDEL key field [field …] | Delete a field specified by key |
| HINCRBY key field increment | Add the increment value to the value corresponding to a certain field of a key |
| HSET key field value | Only when the field does not exist, set the value of the hash table field |
- Zset:
Redis zset 和 set 一样也是string类型元素的集合,且不允许重复的成员。不同的是每个元素都会关联一个double类型的分数。redis正是通过分数来为集合中的成员进行从小到大的排序。zset的成员是唯一的,但分数(score)却可以重复。
| project | Value |
|---|---|
| ZADD key score1 member1 [score2 member2] | Add one or more members to an ordered set, or update the scores of existing members |
| ZRANGE key start stop [WITHSCORES] | Return data within the specified range |
| ZCOUNT key min max | Count the number of members with a specified interval score in an ordered set |
| ZRANK key member | Returns the index of the specified member in the ordered set |
| ZCARD key | Query the number of data corresponding to the key |
| ZREM key member [member …] | Delete element |
| ZINCRBY key increment member | Add a score to an element |
| ZRANGEBYSCORE key min max [WITHSCORES] [LIMIT offset count] | Return data within the specified interval of the score |