title: Filter duplicate rows in mysql by using customer id
body: <p>I have two tables.</p>
  
  <h2>customer table</h2>
  
  <p>It has 3 fields..  </p>
  
  <ol>
  <li>customer_id</li>
  <li>first_name</li>
  <li>last_name</li>
  </ol>
  
  <h2>customer address table</h2>
  
  <p>It has 2 fields</p>
  
  <ol>
  <li>customer_id</li>
  <li>address</li>
  </ol>
  
  <p>My problem is my customer table has 259 rows where as my customer address table has 400+ rows.
  I mean my customer address table contains duplicate rows.</p>
  
  <p>Now i would like select only unique rows from my customer address table... </p>
  
  <p>Can anyone help me?</p>
  
  <p>Thanks </p>