title: Merge two tables to one and remove duplicates
body: <p>I have 2 tables in the same database.</p>
  
  <p>I want to merge them based on the common <code>id</code> column. Because the tables are too huge I am not sure if there are duplicates.</p>
  
  <p>How is it possible to merge these two tables into one based on the <code>id</code> and be sure that there are no duplicates?</p>
  
  <pre><code>SELECT *
  FROM table1,table2
  JOIN
  GROUP BY id
  </code></pre>