title: Merging the data of two columns of the same table into single column
body: <p>I have a single table and the sql query is returning 2 different columns. But I want the result of these two columns in one column and that too having unique results only.</p>
  
  <p>You can also suggest anything if I can do something in Java code to get the desired result, i.e. after fetching the result(s) from the query, any Java code manipulation by which I can arrive at the solution to this problem. </p>
  
  <p>I also don't want to append/ concatenate values of the two columns. 
  I just want the result in one column with unique values only.  </p>
  
  <p>Example:  </p>
  
  <pre><code>Column limitN    Column limitR
       3500            3500
       6500            6500
      10000            7500
      50000           50000
  </code></pre>
  
  <p>So in this case I want the required column values as: </p>
  
  <pre><code>     3500
       6500
       7500
      10000
      50000
  </code></pre>