执行查询进入php页面

I need a query to execute when entering a page (php). I've already added this to the top.

Code:-

mysql_query("INSERT INTO `table_name` (`player_id`, `unit1`, `unit2`, `unit3`, `unit4`)
VALUES ('".$_SESSION['user']['id']."', 0, 0, 0, 0)");

When my users enter the page that contains that, the query should be executed. Yes database connection is included.

How do I fix this? (also will it duplicate player_id)?

First mysql is deprecated use mysqli.

Your query is fine how i can see, but your table could be a problem.

You should not have primary key on player_id if you wish to duplicate player_id. (Otherwise keep the primary key).

Also if you wish to have one player_id with those results (not multiple / duplicates), then you could create query in this way:

$query = "INSERT INTO `table_name` (`player_id`, `unit1`, `unit2`, `unit3`, `unit4`) 
          VALUES ('".$_SESSION['user']['id']."', 0, 0, 0, 0) 
          ON DUPLICATE KEY UPDATE `unit1`=0, `unit2`=0, `unit3`=0, `unit4`=0";

UPDATE:

Also there could be a problem that you are missing a database identifier at mysql_query:

mixed mysql_query ( string $query [, resource $link_identifier = NULL ] )

like mysql_query("MYQUERY", $mylinkISavedAtConnectingToDatabase);