//sql check routine
//check for duplicates in database by stock number
session_start();
unset($_SESSION[error]);
require_once("database.php");
$stock_num=$_POST[stock_num];
$_SESSION[stock_num]=$stock_num;
$sql="SELECT * FROM vehicles where stock_num = '$stock_num'";
$result=mysql_query($sql) or die(mysql_error());
if (mysql_num_rows($result)!=0){
//There is a duplicate stock number so go back to form with an error
$_SESSION[error]="There is a duplicate";
}
if ($_SESSION[error]){
header("Location: newad.php");
}

else {
header("Location: preview_text.php");
}