title: Select distinct rows from two fields
body: <p>I have a table that has millions of records.  </p>
  
  <p>So I might have these columns</p>
  
  <p>a, b, c, d</p>
  
  <p>I need to select all the distinct records based on columns a and b.</p>
  
  <p>But I need to select columns a, b, c and d not just a and b.</p>
  
  <p>Can I do this?</p>
  
  <p><strong>edit</strong></p>
  
  <p>Data might be</p>
  
  <blockquote>
    <p>1,1,frog,green </p>
    
    <p>1,1,frog,brown </p>
    
    <p>2,1,cat,black </p>
    
    <p>2,4,dog,white</p>
  </blockquote>
  
  <p>so i need;</p>
  
  <blockquote>
    <p>1,1,frog,green</p>
    
    <p>2,1,cat,black</p>
    
    <p>2,4,dog,white</p>
  </blockquote>