Your query is selecting all the students who have selected Math only but the Marker field is empty for all the returned students.

Thus I think that students who have selected both are not being included

Below is the input format

Student Id NameSubject Selection Date

10021 john Math 11/1/2011

10021 John Science 11/12/2011

10022 Becky Math 11/2/2011

10022 Becky Science 11/10/2011

10023 Will Math 11/4/2011

10024 Matt Math 11/5/2011

Output desired:

Student Id NameSubjectSelection DateMarker ( Math& Science)

10021 johnMath11/1/20111

10022 BeckyMath11/2/10111

10023 WillMath11/4/20110

10024 MattMath11/5/20110

I appreciate your help.

Thanks,

Blyzzard