Query times out

[kilbey1]

Not sure if this is better for the 'coding' area or a critique. I had much help with this but my query still times out with such large tables. I get the message:
This server is currently overloaded - please try again later

Obviously, this needs to be optimized; I tested this entering only a Social Security number.

The query in question:

<?

function results() {

$aWhere = array(); 
if($_POST['Claimno'] != '') 
  $aWhere[] = 'claimrecord.CRclaimNumber = "' . $_POST['Claimno'] . '"'; 
if($_POST['PTssn'] != '') 
  $aWhere[] = 'patient.PTssn = "' . $_POST['PTssn'] . '"'; 
if($_POST['PTnameLast'] != '') 
  $aWhere[] = 'patient.PTnameLast = "' . $_POST['PTnameLast'] . '"'; 
if($_POST['PTnameFirst'] != '') 
  $aWhere[] = 'patient.PTnameFirst = "' . $_POST['PTnameFirst'] . '"'; 
//test if date range was specified in the form
if($_POST['start_date'] && $_POST['end_date'] != '') 
  $aWhere[] = 'eosdetail.SDserviceDate BETWEEN "' . $_POST['start_date'] . '" AND "' . $_POST['end_date'] . '"'; 


// build where clause 
if($sWhere == 'WHERE ') { 
  $sWhere .= ' AND eosdetail.SDserviceDate BETWEEN "' . $_POST['start_date'] . '" AND "' . $_POST['end_date'] . '"'; 
} else {  

    $sWhere = 'WHERE ' . implode(' AND ', $aWhere);  

}

// Where clause done - add it to the SQL skeleton 
$sql = "SELECT claimrecord.CRclaimNumber, patient.PTssn, patient.PTnameFirst, patient.PTnameLast, eosdetail.SDserviceDate
FROM claimrecord, patient, eosdetail " . $sWhere;

echo $sql . "<P>";
$result = mysql_query($sql) or die(mysql_error());

$num_rows = mysql_num_rows($result);

if($num_rows == 0) {
	echo "<p>No results returned for this query.<P>";
} else {
	echo "<P>found something";
}


}

?>

[kilbey1]

I have improved this, to force a constructed query based ONLY on what the user picks in the form.

<?

function results() {

//set up SELECT statement
$aSelect = array(); 
if($_POST['Claimno'] != '') 
  $aSelect[] = 'claimrecord.CRclaimNumber'; 
if($_POST['PTssn'] != '') 
  $aSelect[] = 'patient.PTssn'; 
if($_POST['PTnameLast'] != '') 
  $aSelect[] = 'patient.PTnameLast'; 
if($_POST['PTnameFirst'] != '') 
  $aSelect[] = 'patient.PTnameFirst'; 
//test if date range was specified in the form
if($_POST['start_date'] && $_POST['end_date'] != '') 
  $aSelect[] = 'eosdetail.SDserviceDate'; 

//set up FROM portion of sql statement
$aFrom = array(); 
if($_POST['Claimno'] != '') 
  $aFrom[] = 'claimrecord'; 
if($_POST['PTssn'] != '') 
  $aFrom[] = 'patient'; 
if($_POST['PTnameLast'] != '') 
  $aFrom[] = 'patient'; 
if($_POST['PTnameFirst'] != '') 
  $aFrom[] = 'patient'; 
//test if date range was specified in the form
if($_POST['start_date'] && $_POST['end_date'] != '') 
  $aFrom[] = 'eosdetail'; 

$resultFrom = array_unique($aFrom);

//set up WHERE portion of sql statement
$aWhere = array(); 
if($_POST['Claimno'] != '') 
  $aWhere[] = 'claimrecord.CRclaimNumber = "' . $_POST['Claimno'] . '"'; 
if($_POST['PTssn'] != '') 
  $aWhere[] = 'patient.PTssn = "' . $_POST['PTssn'] . '"'; 
if($_POST['PTnameLast'] != '') 
  $aWhere[] = 'patient.PTnameLast = "' . $_POST['PTnameLast'] . '"'; 
if($_POST['PTnameFirst'] != '') 
  $aWhere[] = 'patient.PTnameFirst = "' . $_POST['PTnameFirst'] . '"'; 
//test if date range was specified in the form
if($_POST['start_date'] && $_POST['end_date'] != '') 
  $aWhere[] = 'eosdetail.SDserviceDate BETWEEN "' . $_POST['start_date'] . '" AND "' . $_POST['end_date'] . '"'; 

//build SELECT clause
	$sSelect = 'SELECT ' . implode(', ', $aSelect);

// build FROM clause
	$sFrom = 'FROM ' . implode(', ', $resultFrom);

// build where clause 
if($sWhere == 'WHERE ') { 
  $sWhere .= ' AND eosdetail.SDserviceDate BETWEEN "' . $_POST['start_date'] . '" AND "' . $_POST['end_date'] . '"'; 
} else {  

    $sWhere = 'WHERE ' . implode(' AND ', $aWhere);  

}

// Select, Where and From clause done - add it to the SQL skeleton 
$sql = "" . $sSelect . " " . $sFrom . " ". $sWhere;

//echo $sql . "<P>";
$result = mysql_query($sql) or die(mysql_error());

$num_rows = mysql_num_rows($result);

if($num_rows == 0) {
	echo "<p>No results returned for this query.<P>";
} else {
	echo "<P>found something";
}


}

?>