What are the common operation commands for Redis’s basic data type String?

Redis data type String operation command

1. append append string

append name 2222

2. strlen gets the key string length

strlen name

3. Self-increment, self-decrement

Article views, likes can be used This realization.

incr agedecr age

Note that this must be a number to proceed, so a key is reset.

The String type can store not only strings but also numbers.

If you want to bring the step size:

incrby age 5decrby age 8

##4. String range

getrange name 1 3

getrange name 0 -1

View all, similar to the string interception operation in python.

5. Replace the string

Start replacing the string at the specified position

setrange name 0 test

6. Set the value and its expiration time

setex

setex mykey 60 redis

Set the value and its expiration time for the specified key. If key already exists, the SETEX command will replace the old value.

setnx

The Setnx(SET if Not eXists) command sets the specified value for the key when the specified key does not exist. This is often used in distributed locks.

setnx mykey redis333

#key exists, and the setting fails.

7. Batch operations

1. mset, mget

mset, set multiple at one time.

mset k1 v1 k2 v2 k3 v3

mget, get multiple at one time.

mget k1 k2 k3

2. msetnx

Note that when setting multiple values ​​here, as long as one of them fails, none of them will succeed.

msetnx k1 v1 k4 v4

8. Set a json object

In actual applications, you may often need to save an object, so you can use colon: in redis Make some clever designs.

For example, if you want it now

{name: pingguo, age:22}set it to a user1, you can do this:

mset user:1:name pingguo user:1:age 22mget user:1:name user:1:agemset user:1:name pingguo user:1:age 22
 
mget user:1:name user:1:age

9. Getset first gets and then sets

Just like the literal meaning, the value will be obtained first and then set.

If the value does not exist, return
nil. If it exists, get the original value and set the new value.

getset db mongodb

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