SELECT m.tanggal as tanggal, b.nama as uraian, m.dibayar as kas_masuk, '' as kas_keluar FROM pemasukan m
LEFT JOIN biaya b
ON m.biaya=b.id
UNION
SELECT k.tanggal_keluar as tgl, k.nama as uraian, '' as kas_masuk, k.nominal as kas_keluar FROM pengeluaran k