How do I download only filtered data in excel format using PHP?

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PHP

I have to filter table in 3 filters like
date between
branchname and so on
I have tried following code to download filtered data in excel but it shows error
.
The following code works fine when I apply querry like select * from table but it doesn't work when I apply where condition.
here is php code I have tried. Please help if anyone have a solution.

What I have tried:

<?php
include_once("dbconn.php");


if(isset($_POST["getdata"])) {	
$fdate=$_POST['fromdate'];
$tdate=$_POST['todate'];
$clinicbranch=$_POST['clinicbranch'];

$newfollow=$_POST['newfollow'];
$sqlQuery = "select * from patient where billdate  between '$fdate' and '$tdate' AND (clinicbranch='$clinicbranch' OR newfollow='$newfollow')";
$resultSet = mysqli_query($conn, $sqlQuery) or die("database error:". mysqli_error($conn));
$patientData = array();
while( $patient = mysqli_fetch_assoc($resultSet) ) {
	$patientData[] = $patient;
}	

	$fileName = "spanclinic_export_".date('Ymd') . ".xls";			
	header("Content-Type: application/vnd.ms-excel");
	header("Content-Disposition: attachment; filename=\"$fileName\"");	
	$showColoumn = false;
	if(!empty($patientData)) {
	  foreach($patientData as $patientInfo) {
		if(!$showColoumn) {		 
		  echo implode("\t", array_keys($patientInfo)) . "\n";
		  $showColoumn = true;
		}
		echo implode("\t", array_values($patientInfo)) . "\n";
	  }
	}
	exit;  
}
?>