SELECT fname ,  sex FROM Student WHERE StuID IN (SELECT StuID FROM Has_allergy WHERE Allergy  =  "Milk" EXCEPT SELECT StuID FROM Has_allergy WHERE Allergy  =  "Cat")
Find the first name and gender of the student who has allergy to milk but not cat.
SELECT fname , sex FROM Student WHERE StuID IN ( SELECT StuID FROM Has_allergy WHERE Allergy = `` Milk '' EXCEPT SELECT StuID FROM Has_allergy WHERE Allergy = `` Cat '' )
select fname , sex from student where stuid in ( select stuid from has_allergy where allergy = value except select stuid from has_allergy where allergy = value )
Find the first name and gender of the student who has allergy to milk but not cat .