SELECT lc.MACB, COUNT(DISTINCT dc.MAKH) AS SOLUONGKHACH
FROM DATCHO dc JOIN LICHBAY lb ON dc.MACB = lb.MACB
	       JOIN PHANCONG pc ON pc.MACB = lb.MACB
WHERE dc.NGAYDI = lb.NGAYDI AND pc.NGAYDI = lb.NGAYDI
GROUP BY lb.MACB, lb.NGAYDI
HAVING COUNT(DISTINCT pc.MANV) > 3