title: query with less than and greater than statements in where clause
body: <pre><code>SELECT ( Sum(r.marks_attained) / Sum(r.total_marks) * 100 )AS marks,
         s.name
  FROM   result r,
         student s
  WHERE  r.student_id = s.student_id
  GROUP  BY r.student_id
  AND 
  ORDER  BY marks DESC  
  </code></pre>
  
  <p>How i can get only students marks with percentage greater than 90? </p>
  
  <p>can i use marks in where clause?</p>