HSETNX key field value
field in the hash stored at
value, only if
field does not
key does not exist, a new key holding a hash is created.
field already exists, this operation has no effect.
Integer reply, specifically:
fieldis a new field in the hash and
fieldalready exists in the hash and no operation was performed.
redis> HSETNX myhash field “World”
redis> HGET myhash field