Beckham _redis String Type learning

Redisstring type

One, view the command of type string

Second, the operation string example

One, view the command of type string

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 an aid command,

2. Enter [email protected]

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 space is too large, omit some.

second, the operation string example

1. String Type command description

Command name	Description	Format
Set	Associates a string value to a key. If key already holds another value, the set will overwrite the old value, ignoring the type	Set key value
Get	Returns the string value associated with the key. Returns the special value nil if key does not exist	Get key
Setnx	Set the value of key to value when and only if key does not exist. If the given key already exists, then SETNX does not do any action	Setnx Key value
Setex	Associates a value of values to a key and sets the lifetime of the key to seconds (in seconds).	Setex Key seconds value
SetRange	Overwrite (Overwrite) The string value stored by the given key with the value parameter, starting at offset offsets. Non-existent key treated as a blank string	SetRange Key Offset value
Mset	Set one or more key-value pairs at the same time. When a key with the same name is found, Mset overwrites the old value with the new value	Mset key value [key value ...]
Mget	Returns the string value associated with multiple keys. Returns the special value nil if key does not exist	Mget key1 Key2 ...
Append	If the key already exists and is a string, the append command appends value to the original value of the key. If key does not exist, append simply sets the given key to value, just as it does with set key value	Append key value
Msetnx	Set one or more key-value pairs at the same time, when and only if key does not exist. Even if only one key already exists, MSETNX will reject the set operation of all incoming keys	Msetnx key value [key value ...]
GetRange	Returns a substring of the string value in key, where the intercept range of the string is determined by the start and end two offsets (including start and end). A negative offset represents the last count from the string, 1 for the last character, 2 for the penultimate one, and so on	GetRange Key Start end
Getset	Sets the value of the given key to value and returns the old value of key. An error is returned when key exists but is not a string type	Getset Key value
Strlen	Returns the length of the string value stored by key. An error is returned when key is not stored as a string value	Strlen Key
Decr	Subtract one of the numeric values stored in the key. If key does not exist, take 0 as the initial value of key and then perform the DECR operation	DECR key
Decrby	Subtracts the value stored by the key minus the decrement decrement. If key does not exist, take 0 as the initial value of key and then perform the Decrby operation	Decrby Key Decrement
incr	Add one of the numeric values stored in the key. If key does not exist, take 0 as the initial value of key and then perform the incr operation	INCR key
Incrby	Add the value stored by the key to the increment increment. If key does not exist, take 0 as the initial value of key and then perform the Incrby operation	Incrby Key Increment

2. Single string manipulation

2.1. Set key to name, and its value is Xiaobei

127.0.0.1:6379> SetName Xiaobei

Ok

2.2. Get the value of key name

127.0.0.1:6379> Get Name

"Xiaobei"

2.3. Get the character length of key name

127.0.0.1:6379>strlen Name

(integer) 7

2.4. To key name, append character ' 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 good in key name with the great

127.0.0.1:6379>setrange name Great

(integer) 16

127.0.0.1:6379>get Name

"Xiaobeiis Great"

3. Set multiple characters in bulk

3.1. Set key to Name,age, respectively, and its value corresponds to xiaobei,24

127.0.0.1:6379>mset name Xiaobei Age 24

Ok

3.2. Get the value of key for name and age

127.0.0.1:6379>mget name Age

1) "Xiaobei"

2) "24"

4. Self-increment or self-reduction operation

4.1. Self-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. Self-reduction 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. Press 10 for self-increment

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, press 10 for self-reduction

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 Mistakes

5.1, self-increment or decrement only for the numeric string of key or nonexistent key

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 a integer or out of range

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Beckham _redis String Type learning