Delete duplicate records from SQL Server 2012 table with identity -

i trying replicate scenario need delete duplicate rows table except one. rows have unique identity column.

for making things easier, created small test table student , script below.

create table student  (     id int,     rollno int,     name varchar(50),     course varchar(50) ) go  insert student values(1,1335592,'john','biology') insert student values(2,1335592,'john','biology') insert student values(3,1335592,'john','biology') insert student values(4,1335592,'john','biology') insert student values(5,1335593,'peter','biology') insert student values(6,1335593,'peter','biology') insert student values(7,1335593,'peter','biology') go  select * student 

this generate table below.

id  rollno  name    course 1   1335592 john    biology 2   1335592 john    biology 3   1335592 john    biology 4   1335592 john    biology 5   1335593 peter   biology 6   1335593 peter   biology 7   1335593 peter   biology 

i keep records id '1' , '5' in result set , delete else. there way this?.

all appreciated.

thanks shammas

it simple query

delete student  id not in (select min(id)                   student                   group rollno, name, course)