Redis string command

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Command	Explain
APPEND key value	If key already exists and is a string, the APPEND command appends value to the end of the original value of the key. If key does not exist, APPEND simply sets the given key to value as if it were executing set key value.
Set key value	Assigns value to key.
Setnx Key value	Ibid., if key already exists, returns 0. NX is the meaning of not exist. Translator: If key is not exist and then set key value.
Get key	Gets the value of the key. Does not exist return nil
Getset Key value	Sets the value of key and returns the old value.
Mget key1 Key2 ... KeyN	Read the value of more than one key at a time. If the corresponding key does not exist, the corresponding nil is returned.
Mset key1 value1 ... keyN valuen	Setting the value of multiple keys at once, successfully returning 1 means that all values are set, and a failure return of 0 means that no value is set
Msetnx key1 value1 ... keyN valuen	Ditto, but does not overwrite the existing key.
INCR key	Self-increment 1 for key
DECR key	Self-minus 1 for key
Incrby Key Integer	increase by a certain length
Decrby Key Integer	Reduce by a certain length
SUBSTR Key Start end	The subscript starts with 0 and gets the substring of the key.

Redis string command