PHP - Random Unique Numbers

Hi,

First off:
I got a table with two columns and 100.000 rows.
Some of the rows are duplicates (allowing me to "weight" the chance of some rows being hit the first time the script runs)
Allright. This i what I want to do:



When the user clicks a button:
1. Generate a random selected row from the table (this I allready accomplished using this code:

Code: [Select]
<?php

  //CODE FROM WWW.GREGGDEV.COM

  function random_row($table, $column) {

      $max_sql = "SELECT max(" . $column . ") 

                  AS max_id

                  FROM " . $table;

      $max_row = mysql_fetch_array(mysql_query($max_sql));

      $random_number = mt_rand(1, $max_row['max_id']);

      $random_sql = "SELECT * FROM " . $table . "

                     WHERE " . $column . " >= " . $random_number . " 

                     ORDER BY " . $column . " ASC

                     LIMIT 1";

      $random_row = mysql_fetch_row(mysql_query($random_sql));

      if (!is_array($random_row)) {

          $random_sql = "SELECT * FROM " . $table . "

                         WHERE " . $column . " < " . $random_number . " 

                         ORDER BY " . $column . " DESC

                         LIMIT 1";

          $random_row = mysql_fetch_row(mysql_query($random_sql));

      }

      return $random_row;

  }

  

  //USAGE

$randomdata = random_row('MYTABLE', 'MYCOLUMN');

echo $randomdata[2]; // Where [2] is the data I want to extract.


?>

This script works fine. The problem is that I want to exclude the results that have allready been shown. With me?
Therefore, since I have duplicate rows of certain data, I need to exclude all the rows that are the same.

I have a couple of solutions, but I can't seem to fit it into this script. (I will not use the ORDER_BY_RAND() query; it'll be too slow for a table with 100.000 rows)


SO:
Here's ideas I've come up with that might work, but because of my limited experience with PHP and MySQL, haven't been able to accomplish.

1) Insert a "temporary" column in the table which is filled with 1 and 0's where 1 indicates that the row has allready been taken? (If possible)
2) Use PHP sessions to store the previously generated rows?
3) Create a temporary table, which fills up with the allready generated rows by the random script?
4) Create a unique txt-file (e.g: _USERSIPADRESS__.txt) which can be used to save and extract data from the random script? (fopen, fwrite and so fourth)



I hope you understand what I'm trying to do
Any suggestions would be highly appreciated.

Thank you.

How to generate a unique random number in php??? Any one who can help  me?

hi!, is it possible to use rand() to generate unique number that will be saved in a database as a primary key? Since i dont want to have numbers like 00001 incrementing on the table. They dont look like real account numbers... i need something like 45642  or 95452 and the like.

thanks in advance.

I am looking to generate a random number for every user contribution as a title of the contribution.

I could simply check the database each time with a query and generate a number which does not equal to any of the entries of the database. But I imagine this as inefficient and it could become slow if the database is big in my opinion. Also I'd have to contain all the numbers of the database somewhere to manage the "not equals to", in an array or something similar but that can end up as a giant one.

Excuse the layman's speech I am new to this.

Any suggestions how this can be solved efficiently without straining the resources too much? You can explain it linguistically and do not have to provide me any scripts, I will figure it out.

Ello Everyone!

Ok, well I'm making a script with a file uploading thingy, and well, I'm also using a random number to generate a number they must write on a paper and upload it.

Issue: I'm experiencing a slight issue with the random numbers though. Once the user uploads their photo with the numbers, I'll send it to my MySQL database. When it gets to that point the random numbers changes, and the numbers will change. I can not find a way to keep it as is, without it changing until the numbers have been placed into the database.


//Top part

$array = array();
for($i = 0; $i<5; $i++){
$array[$i] = rand(0,20);
}

$randNum = implode($array);


//HTML part
<form method="post" action="" enctype="multipart/form-data">
<table>
<tr>
<td>
Generated Number:
</td>
<td>
<h2>
<?php echo $randNum ?>
</h2>
</td>
</tr>
<tr>
<td>
Group Name:
</td>
<td>
<input type="text" name="group" maxlength="15" />
</td>
</tr>
<tr>
<td>
Photo Taken:
</td>
<td>
<input type="file" name="image"/>
</td>
</tr>
<tr>
<th colspan="2">
<input name="submit" type="submit" value="Register As An Artist"/>
</th>
</tr>
</table>
</form>


//SQL Part
if($copied){
$createArtist = mysql_query("INSERT INTO `artistregister` (user_id, groupname, photo, randomnum) 
VALUES ('".$_SESSION['id']."', '".$groupName."', '".$filePath."', '".$thisRandom."')");
$resetArtist = mysql_query("UPDATE `accounts` SET `isArtist` = '1' WHERE `user_id` = '{$_SESSION['id']}'");
if($createArtist){
if($resetArtist){
echo "Your account is now pending for Artist Access. This could take upto a week.";
$_SESSION['isArtist'] = 1;
}
else{
echo "There was an error, and it had been recorded. Please try again later.";
sendError(mysql_error(), $_SERVER['REQUEST_URI']);
}
}
else{
echo "There was an error, and it had been recorded. Please try again later.";
sendError(mysql_error(), $_SERVER['REQUEST_URI']);
}
}
elseif(!$copied){
echo "There was an error, and it has been recorded. Please try again later.";
sendError("Line 98", $_SERVER['REQUEST_URI']);
}


I've tried looking for different functions, and such, but I'm either not looking in the right place or I'm just making some stupid logical error.

Thank you for looking.