// 1. LAPORAN HARIAN (Hari Ini)
$query_harian = "SELECT transaksi.*, siswa.nama_siswa, jenis_pembayaran.nama_pembayaran 
                 FROM transaksi 
                 JOIN tagihan ON transaksi.id_tagihan = tagihan.id_tagihan
                 JOIN siswa ON tagihan.nisn = siswa.nisn
                 JOIN jenis_pembayaran ON tagihan.id_jenis = jenis_pembayaran.id_jenis
                 WHERE DATE(transaksi.tgl_bayar) = CURDATE()";

// 2. LAPORAN MINGGUAN (7 Hari Terakhir / Minggu Ini)
$query_mingguan = "SELECT ... WHERE YEARWEEK(transaksi.tgl_bayar, 1) = YEARWEEK(CURDATE(), 1)";

// 3. LAPORAN BULANAN (Bulan Berjalan)
$query_bulanan = "SELECT ... WHERE MONTH(transaksi.tgl_bayar) = MONTH(CURDATE()) AND YEAR(transaksi.tgl_bayar) = YEAR(CURDATE())";

// 4. LAPORAN TAHUNAN (Tahun Berjalan)
$query_tahunan = "SELECT ... WHERE YEAR(transaksi.tgl_bayar) = YEAR(CURDATE())";