I want make a query to retrieve only those records from table which are unique on the basis of some coloumns

create table student9(roll int)
insert into student9 values(1)
insert into student9 values(1)
insert into student9 values(2)
insert into student9 values(3)
select distinct * from student9

create table student9(roll int)
insert into student9 values(1)
insert into student9 values(1)
insert into student9 values(2)
insert into student9 values(3)
select distinct * from student9

It is retrieval of unique records from table but I want retrieval of those records which are unique on some coloumns eg if table have 5 coloumns I want to retrieve only those records which are unique on 3 coloumns suppose a student table stores details of all college students I want to retrieve those records which are unique on name and address

It is retrieval of unique records from table but I want retrieval of those records which are unique on some coloumns eg if table have 5 coloumns I want to retrieve only those records which are unique on 3 coloumns suppose a student table stores details of all college students I want to retrieve those records which are unique on name and address

just replace the * with the column names...