.NET/ASP.NET/C#/VB.NET PDF Document SDK

This asks for specific columns from the entity rather than the whole entity. This is legal ESQL, but it would fail at runtime in the context of Example 14-12. That example creates the query with a call to CreateQuery<SalesOrderHeader> on the object context. The generic type argument to CreateQuery SalesOrderHeader here indicates the type of result we re expecting from the query, but this modified query clearly returns something other than a SalesOrderHeader. It returns a couple of columns from each matching entity. When you build a query like this, you get back objects that implement IDataRecord a general-purpose interface used across all of ADO.NET to represent a record (such as a table row) whose columns might not be known until runtime. (This

free barcode software for excel, free excel ean barcode font, excel 2010 free barcode font, how to create barcodes in excel 2013, free barcode font excel 2007, free barcode add in for excel 2007, barcode generator excel template, print barcode labels in excel 2010, barcode plugin excel 2007, barcode format in excel 2007,

is one of the interfaces listed in Table 14-1.) So you d need to use CreateQuery<IDataR ecord> to create such a query, and a suitably modified loop to extract the results:

var query = dbContext.CreateQuery<IDataRecord>( "SELECT o.TotalDue, o.OrderDate " + "FROM AdventureWorksLT2008Entities.SalesOrderHeaders AS o " + "WHERE o.OrderDate = @orderDate", new ObjectParameter("orderDate", orderDate)); foreach (var order in query) { Console.WriteLine(order["TotalDue"]); }

The last test is preceded by a QEXPECT_FAIL macro, which indicates that the test is expected to fail because the image collection fails to check whether an image id exists before adding a tag to it The last line in the test slot removes the database connection used by the image collection This is necessary because the image collection class relies on the default connection If a new image collection object is created (in the next test case, for example), the QtSql module will warn that the database connection is being replaced if the original connection isn t removed Listing 16-23 Testing the tag-keeping capabilities void ImageCollectionTest::testTags() { ImageCollection c; // Make sure that the collection is empty QCOMPARE( cgetTags()count(), 0 ); // At least one image is needed to be able to add tags caddImage( QImage( "test.

Even if you ask for the whole entity as a single column in the SELECT clause, for example:

You wouldn t need the resources of a CompuServe or an America Online to build an application that rendered the text for you! All you had to do was generate HTML, either by coding it directly or writing a server-side application (in C) that would generate it for you Although the Internet had been around for a long time, only at this point was it really being born..

C# is not the only language that runs on the .NET Framework. Indeed, support for multiple languages has always been a key feature of .NET, reflected in the name of its runtime engine, the CLR or Common Language Runtime. As this name implies, .NET is not just for one language numerous languages have access to the services of the .NET Framework class library. Why might you choose C# over the others We already mentioned one important reason: C# was designed specifically for .NET. If you are working with .NET technologies such as WPF or ASP.NET, you ll be speaking their language if you work in C#. Compare this with C++, which supports .NET through extensions to the original language. The extensions are carefully thought out and work well, but code that uses .NET libraries just looks different from normal C++, so programs that bridge the worlds of .NET and standard C++ never feel completely coherent. And the dual personality often presents dilemmas should you use standard C++ collection classes or the ones in the .NET class library, for example In native .NET languages such as C#, such questions do not emerge. But C# is not unique in this respect. Visual Studio 2010 ships with three languages designed for .NET: C#, VB.NET, and F#. (Although VB.NET follows on from its non-.NET Visual Basic predecessors, it was radically different in some important ways. It is a native .NET language with a VB-like syntax rather than VB 6 with .NET capabilities bolted on.) The choice between these languages comes down to what style of language you prefer.