title: Duplicate Rows when self joining tables in SQL
body: <p>I am trying to self join a table together based on the column "Warehouse Number". The goal is to list part numbers, descriptions, and item class of any pairs of parts that are in the same item class and same warehouse. Below is an example of the desired output and starting data.</p>
  
  <p>STARTING DATA</p>
  
  <p><a href="https://i.stack.imgur.com/ChN4t.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ChN4t.png" alt="Starting Data"></a></p>
  
  <p>EXAMPLE OF SOME DESIRED DATA</p>
  
  <p><a href="https://i.stack.imgur.com/QIEJR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QIEJR.png" alt="desired output"></a></p>
  
  <p>However, when that self join happens, there aren't "exact" duplicates but the pairs appear twice in the table.</p>
  
  <p>EXAMPLE OF OUTPUT WITH PROBLEMS (HIGHLIGHTED)
  <a href="https://i.stack.imgur.com/dMeQo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dMeQo.png" alt="PROBLEMS"></a></p>
  
  <p>I have tried most iterations of UNION, INNER JOIN, and other join methods. Is it possible to remove the pairs since it isn't technically an exact duplicate of another row?</p>
  
  <p>Current SQL Code
  <a href="https://i.stack.imgur.com/3S4YB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3S4YB.png" alt="enter image description here"></a></p>