NEED A QUERY

This should do the trick

DECLARE @marks  VARCHAR(500)


DECLARE scursor CURSOR FOR

SELECT MARKS FROM STUDENT


OPEN scursor  
 
FETCH NEXT FROM scursor
                INTO @marks

WHILE (@@FETCH_STATUS = 0)
BEGIN
if @marks between 90 and 99
update STUDENT set GRADE = 'A'
where MARKS between 90 and 99
else
if @marks between 80 and 89
update STUDENT set GRADE = 'B'
where MARKS between 80 and 89
else
if @marks between 70 and 79
update STUDENT set GRADE = 'C'
where MARKS between 70 and 79
else
if @marks between 60 and 69
update STUDENT set GRADE = 'D'
where MARKS between 60 and 69
else
if @marks < 60 
update STUDENT set GRADE = 'E'
where MARKS < 60
print @marks

 FETCH NEXT FROM scursor
                INTO @marks
  END;
CLOSE scursor;
DEALLOCATE scursor;
GO