Redis: operation command of string type data

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Catalog ：

（1）redis Operation commands for string type data

      1.set、2.get、3.append、4.strlen

 （2）redis Operation commands for string type data 2

      1.incr、2.decr、...

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（1）redis Operation commands for string type data

 

String type （string）

The string type is Redis The most basic data type in , It can store any kind of string , Including binary numbers

According to the , Serialized data ,JSON The object is even a picture .

The general idea of string type data operation is through key operation value,key It's a data ID ,value It's our feeling

Business data of interest .

1.set

grammar ：set key value

function ： String value value Set to key in , If key Already exists , The last value will cover the previous value .

Return value ：OK It means success

 

for example ： save String Data of type use Set

 

  If you save key Already exist , Then later vallue, Will take the old value overwrite ：

 

2.get

grammar ：get key

function ： obtain key The string value set in

Return value ：key There is , return key Corresponding value;

                   key non-existent , return nil

   Get stored data use Get：

 

3.append

grammar ：append key value

function ： If key There is , Will value Append to key The end of the original old value

           If key non-existent , Will key Set the value to value

Return value ： The total length after appending the string ( The number of characters )

 

for example ：

 

 

4.strlen

grammar ：strlen key

function ： return  key  The length of the stored string value

Return value ： If key There is , Returns the length of the string value ;

        key non-existent , return 0

for example ： Gets the length of the string ：

 

 （2）redis Operation commands for string type data 2

 

 

1.incr

grammar ：incr key

function ： take key The value of the number stored in plus 1, If key non-existent , be key The value of is initialized to 0 Re execution incr operation .

Return value ： Back to plus 1 After key value

  for example ： to zsage+1 The original value is ：30

When key Value does not exist ：

 

  Give a name ： Give non numerical data +1 Will report a mistake

 

2.decr

grammar ：decr key

function ： take key The number stored in minus 1, If key non-existent , Then key The value of is initialized to 0 Re execution decr operation .

Return value ： Return minus 1 After key value

 

3.incrby

grammar ：incrby key offset

function ： take key The stored value plus the increment value , If key non-existent , be key The value of is initialized to 0 Re execution INCRBY command .

Return value ： Return after increment key value .

  for example ： to zsage+10：

 

4.decrby

grammar ：decrby key offset

function ： take key Subtract the decrement value from the stored value , If key non-existent , be key The value of is initialized to 0 Re execution DECRBY command .

Return value ： Go back to after decrement key value .

for example ： to zsage-10：

 

5.getrange

grammar ：getrange key startIndex endIndex          It will not affect the amount data in the database

function ： obtain key The string values in are derived from startIndex Start to endIndex The ending substring , Include startIndex and endIndex, Negative numbers start at the end of the string ,-1 Represents the last character .

  for example ： Interception acquisition 2-5： The data in the database will not change after interception

Results the same  

 

Get the entire ：

 

6.setrange

grammar ：setrange key offsetIndex value

function ： use value Cover key The stored values of are from offset Start .

Return value ： The length of the modified string .

 

 

for example ：

 

 

 

7.setex

grammar ：setex key seconds value

function ： Set up key Value , And will key The lifetime of is set to seconds ( In seconds )  , If key Already exist , Will overwrite old values .

Return value ： Set up the success , return OK.

  for example ： add to k1 At the same time, set the existence time to 20, Delete after time

 

8.setnx  solve set Set the existing key, Overwrite the original value

grammar ：setnx key value

function ：setnx yes set if not exists Abbreviation , If key non-existent , be set value , If it exists, the value is not set .

Return value ： Set up the success , return 1

Setup failed , return 0

  for example ： The original existence abandons the setting

 

9.mset      Batch addition set take String Type data is added to redis In the database

grammar ：mset key value [key value…]

function ： Set one or more... At the same time key-value Yes

Return value ： Set up the success , return OK.

  for example ：

 

10.mget  Batch acquisition from redis obtain String Data of type

grammar ：mget key [key …]

function ： Get all ( One or more ) Given key Value

Return value ： Contains all the key A list of , If key non-existent , Then return to nil.

  for example ： If not , return nil

 

11. msetnx Batch settings （ add to ） , all key It doesn't exist , Set up the success , otherwise , Setup failed

grammar ：msetnx key value[key value…]

function ： Set one or more... At the same time key-value Yes , If there is a key Is there , The setting is not successful .

Return value ： Set up the success , return 1

Setup failed , return 0

  for example ：