Select * from Student_Info where Math=(select min(Math)from 
Student_Info) or Eng=(select min(Eng) from Student_Info)

create table student7(Roll int,English int,Hindi int,Maths 
int)
insert into student7 values(1,12,15,9)
insert into student7 values(2,23,3,13)
insert into student7 values(3,15,12,4)

select roll from student7 where 
maths=(select min(maths) from student7) 
AND
English=(select min(english)from student7)

Rajesh, AND Operator is used b/w two conditions . Answer 
given by you is limted to two subjects, if there are three 
or more subjects then

Select * from Student_Info where Math=(select min(Math)from 
Student_Info) and Eng=(select min(Eng) from Student_Info)

Select * from (table name)where (field1)=(select
min(field1)from 
table name) and (field2)=(select min(field2) from table name)

Select roll from student
where mark1=(select min(mark1) from student) 
and mark2=(select min(mark2) from student)

Suppose we are having a table called abc which has field 
name as marks, subject and roll
now roll2 and roll3 has the same minimum marks as 40
so the query will be

select roll from abc where marks=(select min(marks) from 
abc)

Select * from marks where 
(Math=(select min(Math)from 
marks) and phy=(select min(phy) from marks)) 
OR
(Math=(select min(Math)from 
marks) and chem=(select min(chem) from marks))
OR
(Phy=(select min(phy)from 
marks) and chem=(select min(chem) from marks))


Sonia if it is 3 subject and will be combine with or clause