MySQL-Error：where子句中的未知列

Question

<div class="ui-widget">

<form method="POST">
<?php

if(isset($_POST['search'])){

$connection = mysql_connect('localhost', 'root', '1234');
mysql_select_db('hoppers');

    $query = "SELECT user_name FROM users WHERE {$_POST['username']} = user_name";
    $result = mysql_query($query) or die ("MySQL-Error: " . mysql_error());
    $row = mysql_fetch_array($result);


if($row = TRUE){

        $present = $row['user_name'];
        echo $present;

     }else{
            echo "This User does not exist!";
        }
}
?>

<label for="tags">Username: </label>
<input type="text" id="tags" name = "username">
<input type="submit" name="search" value="Suchen!">
</form>
</div>

So I'm always getting the this error-message: MySQL-Error: Unknown column 'dompol171' in 'where clause'.
So it is comparing the username that I entered with the column "user_name" itself. I keep freaking out...since I have no clue how to compare it in a different way!

Answer 1

Try using :

 $query = "SELECT user_name FROM users WHERE user_name = '{$_POST['username']}'";