title: How to get data of every first day of month for all month in my sql?
body: <p>I have a table samples. It has data of every day of every month</p>
  
  <pre><code>  date         m1   m2   m3
  '2017-01-01'   10   11    12
  '2017-01-02'   10   10    12
  '2017-01-03'   10   11    12
  '2017-01-04'   10   8     12
  '2017-02-01'   10   6     12
  '2017-02-02'   10   14    12
  </code></pre>
  
  <p>I want the data like this</p>
  
  <pre><code> date         m1   m2   m3
  '2017-01-01'   10   11   12
  '2017-02-01'   10   6    12
  </code></pre>