Question

I would like to only insert a row, if the following SELECT returns a 0 or no rows.

Something like:

IF ( SELECT IS 0) THEN INSERT()

how can I do this in MYSQL ?

I just want to do one query instead of this two queries:

 $r=mysql_query("SELECT `ID`,`Country` FROM `Users` WHERE `IP`='".$ip."'",$connection);

 if(!$r || mysql_num_rows($r) <= 0)
     $ir=mysql_query("INSERT INTO `Users` (`IP`,`Country`) VALUES ('".$ip."','".$country."')",$connection); 

Answer 1

I think what he may be looking for is something along the lines of this answer:

https://stackoverflow.com/a/8185348

EDIT:
Also incase you ever have problems where you need to remove uniqueness or other constraints:

show create table <tablename>

This will show u all the details of the created table..

then you have to drop via the reference that it has
Ex:

UNIQUE KEY <reference_name> (‘value’)

so then you do:

alter table <tablename> drop index <reference_name>