Hello All!

This question probably has a really simple answer but I am fairly new to PHP and I'm not very farmiliar with generating numbers yet. This is what I'm having trouble with:

  • Check MySQL to make sure that this UNIQUE number is not already stored. If it is, generate new number. If not, display number.
  • Generate 9-Digit Number
  • Display 9-Digit Number on Screen in this format: 000-000-000 (With the dashes)

Any help that I can get is MUCH appreciated.


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Maybe not the most elegant solution but it works.

// connect to DB

// run an endless loop
while(1) {

    // generate unique random number
    $randomNumber = rand(0, 999999999);

    // check if it exists in database
    $query = "SELECT * FROM tbl_rand WHERE the_number=$randomNumber";
    $res = mysql_query($query);
    $rowCount = mysql_num_rows($res);

    // if not found in the db (it is unique), break out of the loop
    if($rowCount < 1) {


// pad the number with zeros (if needed)
$paded = str_pad($randomNumber, 9, '0', STR_PAD_LEFT);

// dash delimited string to be displayed
$delimited = '';

// add dashes
for($i = 0; $i < 9; $i++) {

    // add a character
    $delimited .= $paded[$i];

    // add dashes wherever appropriate
    if($i == 2 || $i == 5) {

        $delimited .= '-';

echo $delimited; 

My assumption is that you store numbers in the database as integers between 0 and 999999999. If you store them as strings then the code has to be adapted.

An improvement would be to generate random number and check the database all with an SQL. See this post on SO.

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With regard to your storing, are you going to store as integer, e.g. 374859053 for 374-859-053
and 23 for 000-000-023. In this way, you may find searching is significantly quicker. The dashes can be added after extraction from the db and preceding 0's added for number less than 9 digits long, e.g. with str_pad().

Just a thought.

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