SETNX
Syntax
SETNX key value
Time complexity: O(1)
ACL categories: @write, @string, @fast
Set key to hold string value if key does not exist.
When key already holds a value, no operation is performed.
SETNX is short for "SET if Not eXists".
Return
Integer reply, specifically:
1if the key was set0if the key was not set
Examples
dragonfly> SETNX mykey "Hello"
(integer) 1
dragonfly> SETNX mykey "World"
(integer) 0
dragonfly> GET mykey
"Hello"