Beckham _ redis string type learning, _ redisstring

Beckham _ redis string type learning, _ redisstring

RedisString type

1. View string-type commands

Ii. string operation example

 

 

1. View string-type commands

1. Open the redis client and enter help

127.0.0.1: 6379> help

Redis-cli2.8.19

Type: "help @ <group>" to get a list of commands in <group>

"Help <command>" for helpon <command>

"Help <tab>" to get a listof possible help topics

"Quit" to exit

Note: help is a help command,

2. Enter help @ string

127.0.0.1: 6379> help @ string

APPEND key value

Summary: Append a value to a key

Since: 2.0.0

BITCOUNT key [start] [end]

Summary: Count set bits in a string

Since: 2.6.0

BITOP operation destkey key [key...]

Summary: Perform bitwise operations betweenstrings

Since: 2.6.0

........

Note: because the length is too large, it is omitted.

 

 

 

 

 

Ii. string operation example

1. Description of string commands

Command name	Description	Format
Set	Associate the string value with the key. If the key already holds another value, SET overwrites the old value, regardless of the type.	Set key value
Get	Returns the string value associated with the key. If the key does not exist, a special value nil is returned.	Get key
Setnx	Set the key value to value if and only if the key does not exist. If the given key already exists, SETNX does not take any action	Setnx key value
Setex	Associate the value with the key and set the survival time of the key to seconds (in seconds ).	Setex key seconds value
Setrange	Overwrite the string value stored by the given key using the value parameter, starting from offset. The key that does not exist is treated as a blank string.	Setrange key offset value
Mset	Set one or more key-value pairs at the same time. If a key with the same name exists, MSET overwrites the old value with the new value.	Mset key value [key value...]
Mget	Returns the string value associated with multiple keys. If the key does not exist, a special value nil is returned.	Mget key1 key2...
Append	If the key already exists and is a string, the append Command appends the value to the original value of the key. If the key does not exist, append simply sets the given key as value, just like executing set key value.	Append key value
Msetnx	Set one or more key-value pairs if and only if the key does not exist. Even if only one key already exists, msetnx rejects all key settings.	Msetnx key value [key value...]
Getrange	Returns the substring of the string value in the key. The Truncation range of the string is determined by the offset of start and end (including start and end ). The offset of a negative number indicates that the string is counted from the end,-1 indicates the last character,-2 indicates the second to the end, and so on.	Getrange key start end
Getset	Set the value of the given key to value and return the old value of the key. If the key exists but is not of the string type, an error is returned.	Getset key value
Strlen	Returns the length of the string value stored in the key. If the key is not stored as a string value, an error is returned.	Strlen key
Decr	Reduce the number value stored in the key by one. If the key does not exist, use 0 as the initial value of the key and then perform the decr operation.	Decr key
Decrby	Subtract the decrement value of the key. If the key does not exist, use 0 as the initial value of the key and then perform the decrby operation.	Decrby key decrement
Incr	Add one of the number values stored in the key. If the key does not exist, use 0 as the initial value of the key and then perform the incr operation.	Incr key
Incrby	Add incremental increment to the value stored in the key. If the key does not exist, use 0 as the initial value of the key and then perform the incrby operation.	Incrby key increment

 

 

2. single string operation

2.1 set the key to name and its value to xiaobei.

127.0.0.1: 6379> setname xiaobei

OK

2.2. Obtain the value of key as name.

127.0.0.1: 6379> get name

"Xiaobei"

2.3. Get the length of the character whose key is name

127.0.0.1: 6379> strlen name

(Integer) 7

2.4. The key is name, And the append character is 'is good .'

127.0.0.1: 6379> append name is good'

(Integer) 15

127.0.0.1: 6379> get name

"Xiaobeiis good"

2.5 Replace the key with good in name with great

127.0.0.1: 6379> setrange name 11 great

(Integer) 16

127.0.0.1: 6379> get name

"Xiaobeiis great"

 

3. Set multiple characters in batches

3.1 set key to name and age respectively, and their values correspond to xiaobei, 24

127.0.0.1: 6379> mset name xiaobei age 24

OK

3.2. Obtain the value of key name and age.

127.0.0.1: 6379> mget name age

1) "xiaobei"

2) "24"

 

4. Auto-increment or auto-increment operations

4.1 auto-increment operation

127.0.0.1: 6379> incr c

(Integer) 1

127.0.0.1: 6379> get c

"1"

127.0.0.1: 6379> incr c

(Integer) 2

127.0.0.1: 6379> get c

"2"

4.2. Auto-subtraction operation

127.0.0.1: 6379> decr c

(Integer) 1

127.0.0.1: 6379> get c

"1"

127.0.0.1: 6379> decr c

(Integer) 0

127.0.0.1: 6379> get c

"0"

4.3. Auto-increment by 10

127.0.0.1: 6379> incrby c 10

(Integer) 10

127.0.0.1: 6379> get c

"10"

127.0.0.1: 6379> incrby c 10

(Integer) 20

127.0.0.1: 6379> get c

"20"

4.4. perform auto-reduction based on 10

127.0.0.1: 6379> decrby c 10

(Integer) 10

127.0.0.1: 6379> get c

"10"

127.0.0.1: 6379> decrby c 10

(Integer) 0

127.0.0.1: 6379> get c

"0"

 

5. Common Errors

5.1 auto-increment or auto-increment can only be used for keys of numeric strings or keys that do not exist

127.0.0.1: 6379> set name '1'

OK

127.0.0.1: 6379> get name

"1"

127.0.0.1: 6379> incr name

(Integer) 2

127.0.0.1: 6379> set name 'xiaobei'

OK

127.0.0.1: 6379> get name

"Xiaobei"

127.0.0.1: 6379> incr name

(Error) ERR value is not an integer or out of range

 

Copyright Disclaimer: This article is an original article by the blogger and cannot be reproduced without the permission of the blogger.