title: Left join returning duplicate rows when there is match between two tables and match is not null
body: <p>I am trying to join two table using left join on following tables </p>
  
  <p><strong>Account Table</strong></p>
  
  <pre><code>Zone   ACC_NUM   Profile Status 
  INT    123456    11      Active
  DOM    246810    12      Active
  INT    135791    12      Inactive
  </code></pre>
  
  <p><strong>Meter Table</strong></p>
  
  <pre><code>Acc_Num  Meter
  123456   156894
  135791   NULL
  </code></pre>
  
  <p><strong>Expected Result</strong></p>
  
  <pre><code>   Zone   ACC_NUM   Profile  Status    Meter
      INT    123456    11      Active    156894
      DOM    246810    12      Active    NULL
      INT    135791    12      Inactive  NULL
  </code></pre>
  
  <p>I have written the following query, but I see some duplicates like the results that followed the below query</p>
  
  <pre><code>Select a.Zone, a.Acc_Num, a.Status, m.Meter 
  From Account a
  left join Meter m on m.Acc_Num=a.Acc_Num
  </code></pre>
  
  <p>I got the following results which are not desirable</p>
  
  <pre><code>    Zone   ACC_NUM   Profile  Status    Meter
      INT    123456    11      Active    NULL
      INT    123456    11      Active    156894     
      DOM    246810    12      Active    NULL
      INT    135791    12      Inactive  NULL
  </code></pre>
  
  <p>From above results, I found that when there is match between both the tables and meter is <code>not null</code> it returned duplicate row, one with <code>NULL meter</code> and other with actual value and seems like it's good when there is no match or when there is match but meter is NULL.</p>
  
  <p><strong>May I know a better way to get the expected results?</strong></p>