title: filter a linq query based on the results of another query's results
body: <p>I am wanting to filter a linq query </p>
  
  <p>I have 2 linq statements</p>
  
  <p>The 1st gets all the stores I want and the 2nd is where I filter information based on the results found in the 1st query.</p>
  
  <pre><code>var stores = ctx.Stores.Where(ps =&gt; ps.ParentStoreID == parent.ParentStoreID &amp;&amp; ps.StoreID!=storeID);
  
  var query = (from a in ctx.TransactionTable
            from b in ctx.MappingTable.Where(x =&gt; x.TransactionId== a.TransactionId).DefaultIfEmpty()
               where a.StoreID!=storeID
                   select new
                             {
                                Transactions = a,
                                Mapping = b
                             }).ToList();
  </code></pre>
  
  <p>How do I add another where clause into my 2nd query to only return results where a.StoreId is contained within the stores result?</p>