get a different random value

[kav]

is there a way to get a different number generated by rand() or any other random functions that can do the job?
I wouldnt want to use this, too much process being done if
rand(1,9999)

the program will store random generated number into db. But before it is store, it will check whether the number already exist.

$exist=true;
while($exist){
$num=rand(1,9999);
$result=mysql_query("select auto_no from dbname where auto_no=$num");
if($data=mysql_fetch_array($result))
$exist=true;
else
$exist=false;
}

if there is already number 1 to let say 8888, the possibility of it generating the same number is high. This will cause the loop to goes on and on.
Any ideas? thanks

[TTT]

[OFF TOPIC]
it is as possible to get 8888 again as any other number 😃 😃
[/OFF TOPIC]

don't know is there any way to say like rand(1,9999,{NOT 1,2,3})

there might be better way to do this but, hope this helps:

$b = rand(1,9999);

$q = mysql_query("SELECT id FROM table WHERE rand <= $b ORDER BY rand DESC");

$c = 0;
if(mysql_num_rows($q) != 0) {
   if(mysql_result($q,0,0) == $b) { // exists
     $current = $b;
     for($a=1;$a<$b;$a++) {
         if(mysql_result($q,$a,0) != $b) {
             $a = $b+1;
             // insert
             $c = 1; // has been iserted
         }
     }
     if($c == 1) { // if we have all reserved from $b to 1
       $q = mysql_query("SELECT id FROM table WHERE rand > $b ORDER BY rand DESC");
       /// similar loop as above


 }
   } else {

 // insert
   }

} 


$q = mysql_query("SELECT id FROM table ORDER BY rand");




for($a=0;$a<1;$a++) {
   $b = rand(1,9999);
   $q = mysql_query("SELECT id FROM table WHERE Rnumber = $b");
   if(mysql_num_rows($q) != 0) {

   } else {
   }

}

[juschillinnow]

after querying thr database, you will obviously have to find out which numbers have been used. if numbers 1 - 8888 have already been used, at some point you will have to put the 8888 in a string ($high_rand) and use that to preform another rand...

rand($high_rand, 99999);

It will be very helpful to you to put your database query in a function so that you can call it several times if need be.

[kav]

TTT may i know what is the purpose of below? The variable $a runs into what number?

$q = mysql_query("SELECT id FROM table ORDER BY rand");

for($a=0;$a<1;$a++) {
$b = rand(1,9999);
$q = mysql_query("SELECT id FROM table WHERE Rnumber = $b");
if(mysql_num_rows($q) != 0) {

} else {
}

}