0 ? 'WHERE ' . implode(' AND ', $where) : '';
// Fetch receipts
$receipts = $con->query("SELECT fc.*, s.name, s.enrollment_no, s.father, s.mobile,
c.course_name, ce.institute_name, ce.center_number,
fct.category_name
FROM fee_collections fc
LEFT JOIN students s ON fc.student_id = s.id
LEFT JOIN courses c ON s.course_id = c.id
LEFT JOIN centers ce ON s.center_id = ce.id
LEFT JOIN fee_categories fct ON fc.category_id = fct.id
$where_clause
ORDER BY fc.id DESC");
// Summary
$summary = $con->query("SELECT
COUNT(*) as total_receipts,
SUM(fc.paid_amount) as total_amount,
COUNT(DISTINCT fc.student_id) as total_students,
SUM(CASE WHEN fc.status='Paid' THEN 1 ELSE 0 END) as fully_paid
FROM fee_collections fc
LEFT JOIN students s ON fc.student_id = s.id
$where_clause")->fetch_assoc();
// Centers & filters
$centers = $con->query("SELECT * FROM centers ORDER BY institute_name ASC");
?>