网上图书购销系统的设计 外文翻译.docx

1、网上图书购销系统的设计 外文翻译毕业设计（论文）外 文 翻 译 题 目 网上图书购销系统的设计 专 业 信息管理与信息系统 班 级 09 信管（2） 学 生 张 倩 炜(20907234) 指导教师 胡 元 义 高科学院 2013 年C# and Database Development一、 The Introduce of C# In one sense, C# can be seen as being the same thing to programming languages as .NET is to the Windows environment. Just as Microsof

2、t has been adding more and more features to Windows and the Windows API over the past decade, Visual Basic and C+ have undergone expansion. Although Visual Basic and C+ have ended up as hugely powerful languages as a result of this, both languages also suffer from problems due to the legacies of how

3、 they have evolved.In the case of Visual Basic 6 and earlier, the main strength of the language was the fact that it was simple to understand and didnt make many programming tasks easy, largely hiding the details of the Windows API and the COM component infrastructure from the developer. The downsid

4、e to this was that Visual Basic was never truly object-oriented, so that large applications quickly become disorganized and hard to maintain. As well as this, because Visual Basics syntax was inherited from early versions of BASIC (which, in turn, was designed to be intuitively simple for beginning

5、programmers to understand, rather than to write large commercial applications), it didnt really lend itself to well-structured or object-oriented programs.C+, on the other hand, has its roots in the ANSI C+ language definition. It isnt completely ANSI compliant for the simple reason that Microsoft f

6、irst wrote its C+ compiler before the ANSI definition had become official, but it comes close. Unfortunately, this has led to two problems. First, ANSI C+ has its roots in a decade-old state of technology, and this shows up in a lack of support for modern concepts (such as Unicode strings and genera

7、ting XML documentation), and in some archaic syntax structures designed for the compilers of yesteryear (such as the separation of declaration from definition of member functions). Second, Microsoft has been simultaneously trying to evolve C+ into a language that is designed for high-performance tas

8、ks on Windows, and in order to achieve that theyve been forced to add a huge number of Microsoft-specific keywords as well as various libraries to the language.The result is that on Windows, the language has become a complete mess. Just ask C+ developers how many definitions for a string they can th

9、ink of: char*, LPTSTR, string, CString (MFC version), CString (WTL version), wchar_t*, OLECHAR*, and so on.Now enter .NETa completely new environment that is going to involve new extensions to both languages. Microsoft has gotten around this by adding yet more Microsoft-specific keywords to C+, and

10、by completely revamping Visual Basic into Visual Basic .NET, a language that retains some of the basic VB syntax but that is so different in design that we can consider it to be, for all practical purposes, a new language. Its in this context that Microsoft has decided to give developers an alternat

11、ivea language designed specifically for .NET, and designed with a clean slate. Visual C# .NET is the result. Officially, Microsoft describes C# as a “simple, modern, object-oriented, and type-safe programming language derived from C and C+.” Most independent observers would probably change that to “

12、derived from C, C+, and Java.” Such descriptions are technically accurate but do little to convey the beauty or elegance of the language. Syntactically, C# is very similar to both C+ and Java, to such an extent that many keywords are the same, and C# also shares the same block structure with braces

13、() to mark blocks of code, and semicolons to separate statements. The first impression of a piece of C# code is that it looks quite like C+ or Java code. Behind that initial similarity, however, C# is a lot easier to learn than C+, and of comparable difficulty to Java. Its design is more in tune wit

14、h modern developer tools than both of those other languages, and it has been designed to give us, simultaneously, the ease of use of Visual Basic, and the high-performance, low-level memory access of C+ if required. Some of the features of C# are: Full support for classes and object-oriented program

15、ming, including both interface and implementation inheritance, virtual functions, and operator overloading. A consistent and well-defined set of basic types. Built-in support for automatic generation of XML documentation. Automatic cleanup of dynamically allocated memory. The facility to mark classe

16、s or methods with user-defined attributes. This can be useful for documentation and can have some effects on compilation (for example, marking methods to be compiled only in debug builds). Full access to the .NET base class library, as well as easy access to the Windows API (if you really need it, w

17、hich wont be all that often). Pointers and direct memory access are available if required, but the language has been designed in such a way that you can work without them in almost all cases. Support for properties and events in the style of Visual Basic. Just by changing the compiler options, you c

18、an compile either to an executable or to a library of .NET components that can be called up by other code in the same way as ActiveX controls (COM components). C# can be used to write ASP.NET dynamic Web pages and XMLWeb services.Most of the above statements, it should be pointed out, do also apply

19、to Visual Basic .NET and Managed C+. The fact that C# is designed from the start to work with .NET, however, means that its support for the features of .NET is both more complete, and offered within the context of a more suitable syntax than for those other languages. While the C# language itself is

20、 very similar to Java, there are some improvements: in particular, Java is not designed to work with the .NET environment.Before we leave the subject, we should point out a couple of limitations of C#. The one area the language is not designed for is time-critical or extremely high performance codet

21、he kind where you really are worried about whether a loop takes 1,000 or 1,050 machine cycles to run through, and you need to clean up your resources the millisecond they are no longer needed. C+ is likely to continue to reign supreme among low-level languages in this area. C# lacks certain key faci

22、lities needed for extremely high performance apps, including the ability to specify inline functions and destructors that are guaranteed to run at particular points in the code. However, the proportions of applications that fall into this category are very low.二、 database development processBased on

23、 information engineering information systems planning database is a source of development projects. These new database development projects is usually in order to meet the strategic needs of organizations, such as improving customer support, improve product and inventory management, or a more accura

24、te sales forecast. However, many more database development project is the bottom-up approach emerging, such as information system user needs specific information to complete their work, thus beginning a project request, and as other information systems experts found that organizations need to improv

25、e data management and begin new projects. Bottom-up even in the circumstances, to set up an enterprise data model is also necessary to understand the existing database can provide the necessary data, otherwise, the new database, data entities and attributes can be added to the current data resources

26、 to the organization.Both the strategic needs or operational information needs of each database development projects normally concentrated in a database. Some projects only concentrated in the database definition, design and implementation of a database, as a follow-up to the basis of the developmen

27、t of information systems. However, in most cases, the database and associated information processing function as a complete information systems development project was part of the development.1、 System Development Life CycleGuide management information system development projects is the traditional

28、process of system development life cycle (SDLC). System development life cycle is an organization of the database designers and programmers information system composed of the Panel of Experts detailed description, development, maintenance and replacement of the entire information system steps. This

29、process is because Waterfall than for every step into the adjacent the next step, that is, the information system is a specification developed by a piece of land, every piece of the output is under an input. However shown in the figure, these steps are not purely linear, each of the steps overlap in

30、 time (and thus can manage parallel steps), but when the need to reconsider previous decisions, but also to roll back some steps ahead. (And therefore water can be put back in the waterfall!)Figure 4 on the system development life cycle and the purpose of each stage of the product can be delivered c

31、oncise notes. The system development life cycle including each stage and database development-related activities, therefore, the question of database management systems throughout the entire development process. In Figure 5 we repeat of the system development life cycle stage of the seven, and outli

32、nes the common database at each stage of development activities. Please note that the systems development life cycle stages and database development steps一一exists between the relationship between the concept of modeling data in both systems development life cycle stages between.Enterprise ModelingDatabase development process from the enterprise modeling (system development life cycle stage of the project feasibility studies, and to choose a part), Organizations set the scope and general database content. Enterprise modeling in information systems planning and other