The Redis SETNX command sets a key to a given value, but only if the key doesn’t already exist. If the key already holds a value, no operation is performed.

Note: The SET command can do the same thing, and it’s possible that the SETNX command may be deprecated at some point. Therefore, it’s probably a good idea to use SET instead of SETNX if possible.

In Redis, the MSETNX command allows us to set multiple keys at once, but only if none of them exist.

This allows us to set multiple keys representing different fields of a single logical object in a way that ensures that either all the fields are set, or none are set.

In Redis, the MGET command allows us to get the values of multiple keys at once. The values are returned in an array reply.

If a specified key doesn’t exist, MGET returns nil for that key.

In Redis, the MSET command allows us to set multiple keys at once. It replaces any existing values, just as SET does.

In Redis, the SET command sets a key to hold a given string value.

If the key already holds a value, it is overwritten with the new value. Also, any previous time to live associated with the key is discarded (assuming a successful SET operation).

In Redis, the GET command returns the value of a given key. If the key doesn’t exist, it returns nil.

An error is returned if the value stored at key is not a string.