title: Inner Join with Sum Aggregate function in SQL Server
body: <p>I have three tables StockSummary, Item, ItemSpecification.
  Here I want to join these three tables and to get Sum(StockSummary.Quantity).
  The main Columns are as follows:</p>
  
  <pre><code>TableA: StockSummary(ItemID, Quantity)
  TableB: Item(ItemID, ItemName, SpecificationID)
  TableC: ItemSpecification(SpecificationName, SpecificationID)
  </code></pre>
  
  <p>The desired result should give ItemName, SpecificationName and SUM(Quantity). How to use Aggregate function in Inner Joins?</p>