title: How do i get max salary row , group by country
body: <pre><code>------------------------------------------------
  country |   salary  |   name    |   adress  
  ------------------------------------------------
  India   |   10000   |   ch1     |   something
  japan   |   20000   |   ch2     |   nothing
  india   |   25000   |   ch3     |   hjsdj
  japan   |   30000   |   ch4     |   hjhjhj
  </code></pre>
  
  <p>I need to get max salary in japan and also in india with adress, name.</p>