title: Data type conversion in SQL query
body: <p>I have the following query in which I am trying to add two columns which are of data type <code>nvarchar</code>. It is giving me only concatenation. Please have a look on query that is written below:</p>
  
  <pre><code>SELECT 
      T0.[ItmsGrpCod],
      T1.[Dscription],
      T3.[OnHand] as 'Opening balance',
      (T1.[U_TotalGraded]) + (T1.[U_TotalRej]),
      T1.[U_TotalGraded], T1.[U_TotalRej], 
      T2.[DocDate] 
  FROM 
      OITM T0
  INNER JOIN 
      IGN1 T1 ON T0.[ItemCode] = T1.[ItemCode] 
  INNER JOIN 
      OIGN T2 ON T1.[DocEntry] = T2.[DocEntry] 
  INNER JOIN 
      OITW T3 ON T0.[ItemCode] = T3.[ItemCode]
  </code></pre>
  
  <p>Now if <code>T1.[U_TotalGraded] = 12</code> and <code>T1.[U_TotalRej] = 3</code> then I am getting <code>(T1.[U_TotalGraded])+(T1.[U_TotalRej]) = 123</code>  instead of adding.</p>