title: Student not present against student recorded subject wise
body: <p>I have a student monthly table in mysql
  I recorded every days of month 1,2,3,4,5,6..31 in recorded_day column. with subject wise like math,science,English..etc</p>
  
  <p>Month table like:</p>
  
  <pre><code>subject          recorded_day
  Math              1
  science           1
  English           1
  Math              2
  science           2
  English           2
  Math              4
  science           4
  English           4
  Math              7
  science           8
  English           9
  </code></pre>
  
  <p>how to write query for retrieving data separated subject wise student not present in class.
  i wants retrieve the recorded_day which date student not present in subject wise class</p>
  
  <p>output like</p>
  
  <pre><code>subject       recorded_day not present
  Math        3,5,6,8,9,10...31
  science     3,5,6,7,9......31
  English     3,5,6,7,8,10,...31
  </code></pre>