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copied!<p>I'm going to try to convince you that:</p> <ul> <li>The two methods you proposed give the same performance.</li> <li>There are at least two non-performance related reasons you should prefer <code>==</code>.</li> <li>There is another separate improvement that you can make to your code to reduce the possibility of errors.</li> </ul> <p>To see that the performance will be the same, look at the SQL generated in each case. This test program shows you how you can view the generated SQL:</p> <pre><code>int orderId = 4; TextWriter textWriter = new StringWriter(); using (var dc = new DataClasses1DataContext()) { dc.Log = textWriter; Order o1 = dc.Orders.FirstOrDefault(x => x.OrderId == orderId); Order o2 = dc.Orders.FirstOrDefault(x => x.OrderId.Equals(orderId)); } string log = textWriter.ToString(); </code></pre> <p>The SQL sent in each case is the same, as you can see by inspecting the log:</p> <pre><code>SELECT TOP (1) [t0].[OrderId], [t0].[CustomerID], [t0].[Date], [t0].[Description] FROM [dbo].[Order] AS [t0] WHERE [t0].[OrderId] = @p0 SELECT TOP (1) [t0].[OrderId], [t0].[CustomerID], [t0].[Date], [t0].[Description] FROM [dbo].[Order] AS [t0] WHERE [t0].[OrderId] = @p0 </code></pre> <p>Regarding whether to use <code>==</code> or <code>Equals</code>, firstly I'd suggest using <code>==</code> for readability. This is the idiomatic way to compare two integers in C#.</p> <p>Secondly with <code>==</code> you will get a compile time error if you give objects of different (incompatible) types. I assume that in your case <code>order</code> has type int, but let's assume that someone else wrote this code and accidentally made an error where <code>order</code> is a variable of type <code>Order</code> instead of an <code>int</code>. Now let's compare what would happen in each case:</p> <pre><code>Order order = new Order { OrderId = 4 }; x.OrderId.Equals(order) // This compiles, but you get an exception at runtime: // Could not format node 'Value' for execution as SQL. x.OrderId == order // Compile error: Operator '==' cannot be applied to // operands of type 'int' and 'Order' </code></pre> <p>It is better to get compile time errors than runtime errors, so prefer to use <code>==</code> in this case.</p> <p>Finally, if you only expect one result you should prefer to use <code>SingleOrDefault</code> instead of <code>FirstOrDefault</code> as the former will throw an exception if there are two matching objects found instead of just returning the first. This extra check will cost a tiny amount in performance but again allows you to catch errors earlier. If performance is a critical issue for you, instead of removing these safety checks you should consider fetching multiple objects from the database at once, not one object at a time.</p> <p>So in summary I recommend that you use this:</p> <pre><code>Album album = db.Albums.SingleOrDefault(x => x.OrderId == orderId); </code></pre>

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