Mathematics. (Table)
Roll Mmarks Name

30. X Roy

40. P De

50. Z roy

60. P roy

75. Q De
Computer(Table)
Roll Compmarks

70
2 50
3 60
4 80
5 90
Query.1
List roll of students who got > 50 either in mathematics or computer
Query.2
List roll of students who got >50 both in mathematics and computer