[introduction series of redis] data types and related commands of redis

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Preface

And then learn Redis Data types and some related instructions , I will continue to practice ！

redis Start command and key command

Start command

Redis The command is used in the redis Perform operations on the service .
To be in redis To execute commands on the service, you need to start redis Server side .Redis The server downloaded it before us redis In the installation package of .

 Start command ：redis-server

After starting the server , Another one cmd Start client .
To be in redis Executing commands on a service requires a redis client .Redis The client downloaded before us redis In the installation package of .

 Start command ：redis-cli

No pictures are posted here , This part has been implemented during the installation of the previous section , You can go back to see what you want to see ！

Key command

redis Key commands must be used in conjunction with data type commands , Here we first separate him , have a look redis What key commands are there , Probably remember , Later, the actual operation of data types will use ！
（ Command keywords are not case sensitive ）

DEL key
-  This command is used in  key  Delete... When it exists  key.

EXISTS key
-  Check the given  key  Whether there is 

EXPIRE key seconds
-  For a given  key  Set expiration time , In seconds .

PERSIST key
-  remove  key  The expiration time of ,key  Will last .

TTL key
-  Returns... In seconds  key  The remaining expiration time of .

RENAME key newkey
-  modify  key  The name of .

TYPE key
-  return  key  The type of value stored .

There are so many commands in common use , The actual operation and data type are put below .

redis data type

Redis Five data types are supported ：string（ character string ）,hash（ Hash ）,list（ list ）,set（ aggregate ） And zset(sorted set： Ordered set ).
His data operation behavior is still to save , modify , Delete , obtain .
Attached below is a carefully drawn diagram to see the differences between these five data types ：

String（ character string ）

The string type is Redis The most basic data storage type in , He was in Redis Is binary safe , This means that the type can accept data in any format , Such as JPEG Image data or Json Object description information, etc , stay Redis Of string type Value The maximum length of data that can be held is 512M.

SET key value
- Set the specified  key  Value .

MSET key value [key value ...]
- Set one or more... At the same time  key-value  Yes .

GET key
- Get specified  key  Value .

MGET key1 [key2..]
- Get all ( One or more ) Given  key  Value .

Pictured ,help+ The instruction word can print out the usage of the instruction .
Next, try setting the expiration time for the key ：

Pictured , Before not setting, the value is -1, Set ten second expiration , The value after expiration is -2, This value disappears
Why should we practice this key Overdue , because Some scenes key Expiration is important , for example ： Verification Code （ The verification code expires after a period of time ）.
Okay , There are so many string instructions , Please learn more instructions by yourself ！

Hash（ Hash ）

Redis hash It's a string Type of field（ Field ） and value（ value ） Mapping table ,hash Ideal for storing objects . Like a shopping cart , You can use it hash Storage .
Look at the picture above, it's a big key , His value is divided into keys - value .

HDEL key field1 [field2]
-  Delete one or more hash table fields 

HLEN key
-  Get the number of fields in the hash table 

HGET key field
-  Gets the value of the specified field stored in the hash table .

HGETALL key
-  Gets the specified in the hash table  key  All fields and values of 

HMGET key field1 [field2]
-  Get the value of all the given fields 

HKEYS key
-  Get all the fields in the hash table 

HVALS key
-  Get the values in all hash tables 

HSET key field value
-  Hash table  key  In the field  field  The value of the set  value .

HMSET key field1 value1 [field2 value2 ]
-  There will be more than one  field-value ( Domain - value ) Set to hash table  key  in .

Be careful ：HDEL key field1 [field2] Delete hash One of the field, Small key ,DEL key It's this hash Delete , Delete the big key .

List（Redis list )

Redis List is a simple list of strings , Sort by insertion order . You can add an element to the head of the list （ On the left ） Or tail （ On the right ）

LPUSH key value1 [value2]
-  Insert one or more values into the list header （ On the left ）

RPUSH key value1 [value2]
-  Add one or more values... To the list （ On the right ）

LRANGE key start stop
-  Get the elements in the specified range of the list ,start from  0  Start , And start and stop The values of all contain 

LREM key count value
-  Remove list elements 
-  Put the list before count The value of the second occurrence is value Remove the elements of 
- count > 0: Remove from the beginning to the end 
- count < 0: Remove from the tail to the head 
- count = 0: Remove all 


LSET key index value
-  Set the value of the list element through the index 

LLEN key
-  Get list length 

LINDEX key index
-  Get the elements in the list by index 

LINSERT key BEFORE|AFTER pivot value
-  Insert an element before or after a list element 

LPOP/RPOP key
 Move out and get the first element of the list / The last element 

Please learn other instructions by yourself ！

Set（ aggregate ）

Redis Of Set yes String Unordered collection of type . Collection members are unique , This means that duplicate data cannot appear in the collection .
The code of the collection object can be intset perhaps hashtable.
Redis The middle set is implemented through a hash table , So add the , Delete , The complexity of searching is O(1).

notes ： Collection has no update operation

SADD key member1 [member2]
-  Add one or more members to the collection 

SCARD key
-  Get the number of members of the collection 

SMEMBERS key
-  Returns all members of the collection 

SREM key member1 [member2]
-  Remove one or more members of the collection 

SMOVE source destination member
-  take  member  Elements from  source  The assembly moves to  destination  aggregate 

SPOP key
-  Remove and return a random element from the collection 

Please learn other instructions by yourself ！

sorted set（zset）（Redis Ordered set ）

Redis An ordered set is the same as a set string Collection of type elements , And duplicate members are not allowed .
The difference is that each element is associated with a double Score of type .redis It's the scores that sort the members of a collection from small to large .
Members of an ordered set are unique , But fractions (score) But it can be repeated .
Collections are implemented through hash tables , So add the , Delete , The complexity of searching is O(1).

ZADD key score1 member1 [score2 member2]
-  Add one or more members... To an ordered collection , Or update scores of existing members 

ZRANGE key start stop [WITHSCORES]
-  Return the members in the specified interval of the ordered set through the index interval 

ZRANGEBYSCORE key min max [WITHSCORES] [LIMIT]
-  Returns the members of an ordered set in a specified interval through scores 

ZRANK key member
-  Returns the index of a specified member in an ordered collection 

ZREM key member [member ...]
-  Remove one or more members of an ordered collection 

ZREMRANGEBYSCORE key min max
-  Remove all members of a given fraction interval from an ordered set 

Please learn other instructions by yourself ！

Conclusion

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