title: Prevent duplicates across multiple executions of copying records back into source table while changing one column
body: <p>I want to select <code>CustomerID</code>, <code>OrderTypeID</code>, and <code>LoanNumber</code> from <code>tblOrder</code> and insert it with a new <code>OrderTypeID</code> but same <code>CustomerID</code> and <code>LoanNumber</code>.
  My query does that but it duplicates the values, every time the query is executed it duplicates the rows.</p>
  <pre><code>insert into tblOrder (CustomerID, OrderTypeID, LoanNumber)
  Select o.CustomerID,3, o.LoanNumber
  from tblOrder as o
  where o.OrderTypeID = 1;
  </code></pre>
  <p>this is what the query does:</p>
  <p>OrderID 9 - 12 are duplicates or OrderID 5 - 8. The query was executed 2 times hence the records got duplicated.</p>