MySQL: Generate serial number

I have a table: student_marks

marks
-----
  44
  55
  64
  98
  76

Expected output:

serial_number|marks
--------------------
  1          | 44
  2          | 55
  3          | 64
  4          | 98
  5          | 76

Solution:

Based on your reasons for not wanting to use user defined variables as wanting to avoid having 2 queries, one for inializing and one to use it you could use the following:

SELECT @a:=@a+1 serial_number, marks FROM student_marks, (SELECT @a:= 0) AS a;