c# qr code generator dll Subqueries, Table Expressions, and Ranking Functions in visual C#.net

Paint QR Code ISO/IEC18004 in visual C#.net Subqueries, Table Expressions, and Ranking Functions

As a user-defined datatype, you might, for example, create an ADDRESS type, with STREET, NUMBER, POSTALCODE, and CITY components. You can create arrays of user-defined datatypes. For example, you could use the ADDRESS type to add an array of addresses to the OFFERINGS table. That would allow you to store multiple alternative location addresses for course offerings. If you want to store only a single location address, you obviously don t need an array a regular user-defined address type would be sufficient.

The first noticeable aspect of SQL that is different than other programming languages is the order in which the code is processed. In most programming languages, the code is processed in the order in which it is written. In SQL, the first clause that is processed is the FROM clause, while the SELECT clause, which appears first, is processed almost last. Each step generates a virtual table that is used as the input to the following step. These virtual tables are not available to the caller (client application or outer query). Only the table generated by the final step is returned to the caller. If a certain clause is not specified in a query, the corresponding step is simply skipped. Following is a brief description of the different logical steps applied in both SQL Server 2000 and SQL Server 2005. Later in the chapter, I will discuss separately the steps that were added in SQL Server 2005.

The purpose of this book is to explain how to develop applications for the .NET Framework. Specifically, this means that I intend to explain how the CLR works and the facilities it offers. I ll also discuss various parts of the FCL. No book could fully explain the FCL it contains literally thousands of types, and this number is growing at an alarming rate. So, here I m concentrating on the core types that every developer needs to be aware of. And while this book isn t specifically about Windows Forms, XML Web services, Web Forms, and so on, the technologies presented in the book are applicable to all these application types. With this book, I m not attempting to teach you any particular programming language. I m assuming that you re familiar with a programming language such as C++, C#, Visual Basic, or Java. I also assume that you re familiar with object oriented programming concepts such as data abstraction, inheritance, and polymorphism. A good understanding of these concepts is critical because all .NET Framework features are offered via an object oriented paradigm. If you re not familiar with these concepts, I strongly suggest you first find a book that teaches these concepts. Although I don t intend to teach basic programming, I will spend time on various programming topics that are specific to the .NET Framework. All .NET Framework developers must be aware of these topics, which I explain and use throughout this book. Finally, because this is a book about the .NET Framework s common language runtime, it s not about programming in any one specific programming language. However, I provide lots of code examples in the book to show how things really work. To remain programming language agnostic, the best language for me to use for these examples would be IL (intermediate language) assembly language. IL is the only programming language that the CLR understands. All language compilers compile source code to IL, which is later processed by the CLR. Using IL, you can access every feature offered by the CLR. However, using IL assembly language is a pretty low level way to write programs and isn t an ideal way to demonstrate programming concepts. So I decided to use C# as my programming language of choice throughout this entire book. I chose C# because it is the language Microsoft designed specifically for developing code for the .NET Framework. If you ve decided not to use C# for your programming projects, that s OK I ll just assume that you can read C# even if you re not 12

Installing SQL Server (Part Two)

A. Incorrect: An ASPX page is a webpage in ASP.NET and not a user control. In addition,

TABLE 10-1

You might also wonder how we could know what the latest version number is at which each row was last modified . We can find that by using the VERSION option of the CHANGETABLE function as follows:

One of the neater features I implemented in WDBG was the Debug Break menu option. This option means that you can break into the debugger at any time while the debuggee is running. In the first edition of this book, I went through a huge explanation of a technique in which I suspended all the debuggee threads, set a one-shot breakpoint in each thread, and to ensure the breakpoints executed, posted WM_NULL messages to the threads. (To find out more about one-shot breakpoints, see the section "Step Into, Step Over, and Step Out" later in this chapter.) It took quite a bit of code to get it working, and it generally worked fairly well. However, in the one case in which it didn't work, all the debuggee's threads were deadlocked on kernel-mode objects. Since the threads were suspended in kernel mode, there was no way I could bump them back down to user mode. I had to do all this work and live with the limitation of my implementation because WDBG needed to run on Windows 98 and Microsoft Windows Me as well as on Windows NT based operating systems. Since I dropped support for Windows 98 and Windows Me, implementing the Debug Break menu became absolutely trivial and always works. The magic is the wonderful function CreateRemoteThread, which isn't available on Windows 98 or Windows Me but is available on Windows 2000 and later. Another function that achieves the same effect as CreateRemoteThread but is available only on Windows XP and later is DebugBreakProcess. As you can see from the following code, the implementation of the function that does the work is simple. When the remote thread executes the DebugBreak call, I just treat the resulting breakpoint exception as if it were a user-defined breakpoint in the exception handling code. HANDLE LOCALASSIST_DLLINTERFACE __stdcall DBG_CreateRemoteBreakpointThread ( HANDLE LPDWORD { HANDLE hRet = CreateRemoteThread ( hProcess NULL 0 (LPTHREAD_START_ROUTINE)DebugBreak 0 0 lpThreadId return ( hRet ) ; } Although it might appear risky to pop a thread into a debuggee, I felt it was safe enough, especially because this is the exact same technique that WinDBG uses to affect its Debug Break menu. However, I do want to mention that there are side effects from calling CreateRemoteThread. When a thread starts in a process, the contract it has with the operating system is that it will call each DllMain for all loaded DLLs that haven't called DisableThreadLibraryCalls. Correspondingly, when the thread ends, all those DllMain functions that were called with the DLL_THREAD_ATTACH notification will be called with the DLL_THREAD_DETACH notification as well. This all means that if you have a bug in one of your DllMain functions, the CreateRemoteThread approach of stopping the debuggee could exacerbate the trouble. The odds are slim, but it's something to keep in mind. , , , , , , ) ; hProcess lpThreadId , )