Error Handling to stop query outputting all table results

[Sallie_ann]

I have written a query that outputs records from a MySQL database when the user selects an option. However, if no option is selected all records in the database table are returned. How do I insert a break in the code that will tell the user to select an option and stop this happening? My code is as follows;

$whereclause = $where1;

if ($whereclause == "") {
$whereclause = $where2;
} else if ($where2 == " ") {
$whereclause = $where3;
} else if ($where3 == " ") {
$whereclause = $where4;
} if($whereclause != "") {
$whereclause = " WHERE " . $whereclause;
}

$sql = "SELECT name, County, sector, company_size
FROM beacon
$whereclause";

$result = mysql_query($sql) or die("Error");

[barand]

Your problem is that you are still going ahead and using an empty WHERE clause

$whereclause = $where1; 
if ($whereclause == "") { 
$whereclause = $where2; 
} else if ($where2 == " ") { 
$whereclause = $where3; 
} else if ($where3 == " ") { 
$whereclause = $where4; 
} 
if($whereclause != "") { 
   $whereclause = " WHERE " . $whereclause; 
   $sql = "SELECT name, County, sector, company_size 
   FROM beacon 
   $whereclause"; 

   $result = mysql_query($sql) or die("Error");

   // process results here
} 
else {
   echo "Please select an option";

// return to form for user to input option
   header("location: myform.php");
}

hth