用户名冲突的解决方案

Question

Here's my PHP code - it checks to see if a username exists and if it does it adds a "_" and an ascending number to it.

$username starts as a user entered Username.

$usernameCopy = $username;
$appendNum = 1;
$userOK = false;
while( $userOK == false )
{
    $query = "SELECT ua.id 
    FROM someDB.users_accounts ua
    WHERE ua.user = '$username'; ";

    $resultID = mysqli_query($linkID, $query) or die("Data not found. USERNAME");
    $numRows = mysqli_num_rows($resultID);
    if( $numRows <> 0)
    {
        //USER ALREADY EXISTS
        $appendNum = $appendNum + 1;
        $username = $usernameCopy . '_' . $appendNum;
    }
    else
    {
        $userOK = true;
    }
}

Then I use the $username.

Is it possible to do something like this is a single SQL query?

Answer 1

For unique username, you can use like this.

$firstname = "Testing";
$username=preg_replace('/[^a-zA-Z0-9]/s', '', $firstname). $this->generateRandomString(5);

Function generateRandomString,

function generateRandomString($length = 5) 
{
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, strlen($characters) - 1)];
    }
    return $randomString;
}