mysql - PHP caches RAND() variable values -

i have following code in file index.php:

include('db_connect.php'); //here's script provides mysql connection database  $a = round(rand(1,100)); $b = round(rand(160,202)); $c = round(rand(50,110)); $d = round(rand(1,99999));  $sql = "insert sinstance (p1,p2,p3,p4) values ('".$a."','".$b."','".$c."','".$d."')"; $result = mysql_query($sql) or die(mysql_error()); 

obviously, randomly generates values , inserts them record myisam database table sinstance.

the problem: after ~1000 records generated & inserted, it's impossible generate new records (with unique sets of values). every new record clone of old 1 (with same p1-p2-p3-p4 values).

the question: how avoid , make php generate unique records?

the clue: server-side problem php, somehow caches values set of rand() function. problem not connected neither browser, nor mysql itself.

not sure if you're not doing wrong, reseting random seed generator trick :

http://php.net/manual/en/function.srand.php