This is your application. in VB.NET

Drawer QR Code ISO/IEC18004 in VB.NET This is your application.

Why do I think that database documentation is even more important than user documentation or functional specifications It s because of the impact the document will have on the user s data. If you have a documented database, you can make guesses about the functional specification, and probably come pretty close. If you lack user documentation, you can always write it when the program is done (as though there was any other way ). But if you lack database documentation, you are in for a world of hurt. If you haven t worked on large database projects before, you might not believe me. But I have. I once inherited an existing enterprise-wide database system written in Visual Basic 3.0. The source code was bad enough, but the associated undocumented 100-table database was a mishmash of inconsistently stored data values. The confusing stored procedure code wasn t much better. Since there wasn t a clear set of documentation on each field, the six programmers who originally developed the system had each made their own decisions about what range of data would be allowed in each field, or about which fields were required or not.

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Tracing back through the uncommented 100,000 lines of source code to determine what every field did was not fun, and it took a few months to complete it with accuracy. Since the customer had paid for and expected a stable and coherent system, most of the extra cost involved in replacing the documentation that should have been there in the first place was borne by my development group. Don t let this happen to you!

Summary

Most Visual Basic applications target the business world and are designed to interact with some sort of database. Understanding the database system used with your application is important; even more important is documenting the specific database features you incorporate into your application. Because of the influence of relational databases and the SQL language on the database industry, it won t be hard to find a lot of resources to assist you in crafting SQL statements and complex data analysis queries. The Library Project in this book uses SQL Server 2005, but because of the generally consistent use of the core SQL language features, the application could just as easily have used Oracle, Microsoft Access, or any of a number of other relational databases.

To assist in my development of Visual Basic database projects, I always write a Technical Resource Kit document before I begin the actual coding of the application. The bulk of this word processing document consists of the table- and field-level documentation for the application s associated database. Also included are the formats for all configuration and custom datafiles, a map of the online help pages, and information about third-party products used in the application. Depending on the type of application, my expectations for the user, and the terms of any contract, I may supply none, some, or all of the Resource Kit s content to the user community. Let s begin the Technical Resource Kit for the Library Project by designing and documenting the database tables to be used by the application. This Resource Kit appears in the book s installation directory, in the 4 subdirectory, and contains the following three files: ACME Library Resource Kit.doc A Microsoft Word version of the technical documentation for the project ACME Library Resource Kit.pdf A second copy of the Technical Resource Kit, this time in Adobe Acrobat (PDF) format Database Creation Script.sql A SQL Server database script used to build the actual tables and fields in the database

This section includes a listing of the tables included in the Library database. Each table includes a general description to assist you in your understanding of the database structure. You will encounter all of these tables in successive chapters, along with associated source code, so don t freak out if some table or field seems unknowable right now.