Filtering MYSQL results by date - php

Question

We have a script that generate invoice once a month (cron). But we would like to add feature, that we would be able to select date range "from - to" and then generate invoice only for the date selected.
I guess making input fields with calendar pop-up isn't hard, but filtering with PHP is a bit bigger challenge, so if anyone want to take a look at my code and give me some tips, I would be grateful.
function genInvoice($clientID, $orderID=0, $paid=false)
{
if($orderID == 0)
$sql = "select tblorders.* from tblorders,tblusers where invoiceid=0 and tblorders.userid=tblusers.id " .
"and status='closed' and tblusers.clientid=" . $clientID;
else
$sql = "select tblorders.* from tblorders,tblusers where invoiceid=0 and tblorders.userid=tblusers.id " .
"and tblusers.clientid=" . $clientID . " and tblorders.id=" . $orderID;
$res = full_query($sql) or die(mysql_error());
// If no closed orders uninvoiced, just return
if(!mysql_num_rows($res))
return 0;
$amount = 0;
$orders = array();
while($row = mysql_fetch_array($res, MYSQL_ASSOC))
{
// print_r($row);
// print "<br><hr>";
$amount += $row['amount'];
$orders[] = $row['id'];
}
$date = date("Y-m-d");
$status = $paid ?'Paid' : 'Unpaid';
$sql = "insert into tblinvoices (clientid, date, duedate, subtotal, total, status) values (" . $clientID . ",'" . $date .
"','" . $date . "'," . $amount . "," . $amount . ",'" . $status . "')";
$res = full_query($sql) or die(mysql_error());
$invoiceid = mysql_insert_id();
$sql = "update tblorders set invoiceid=" . $invoiceid . " where id in (" . implode(",", $orders) . ")";
$res = full_query($sql) or die(mysql_error());
$sql = "select tblorders.id as ReportID, FirstName, LastName, SearchName, CountyID, StateID, bl_orderitems.userid, bl_orderitems.amount, " .
"bl_orderitems.notes from tblorders, bl_orderitems left join bl_search on bl_search.id=packageid where tblorders.id in (" .
implode(",", $orders) . ") and bl_orderitems.orderid=tblorders.id order by tblorders.id,bl_orderitems.id";
$res = full_query($sql) or die(mysql_error());
while($row = mysql_fetch_array($res, MYSQL_ASSOC))
{
if($row['CountyID'] != 0)
$locale = getCounty($row['CountyID']);
else if($row['StateID'] != 0)
$locale = getState($row['StateID']);
if($row['SearchName'] != "")
$description = mysql_real_escape_string($row['FirstName'] . " " . $row['LastName'] . " " .
$row['SearchName'] . " " . $locale . " (Order #" . $row['ReportID'] . ")");
else
$description = "Search Package: " . mysql_real_escape_string($row['notes'] . " (Order #" . $row['ReportID'] . ")");
$sql = "insert into tblinvoiceitems (invoiceid, userid, type, description, amount, duedate) values " .
"(" . $invoiceid . "," . $row['userid'] . ",'search','" . $description . "','" .
$row['amount'] . "','" . $date . "')";
// print $sql . "<br>";
full_query($sql) or die(mysql_error());
}
sendmessage ('Invoice Created', $invoiceid);
return $invoiceid;
}

Answer 1

not going to look through all that code, but filtering results by a date range is easy.
SELECT id FROM some_table WHERE some_date_field BETWEEN $first_date AND $second_date