tailieunhanh - Java Database Programming Bible- P2

Java Database Programming Bible- P2: Welcome to Java Database Programming Bible. This book is for readers who are already familiar with Java, and who want to know more about working with databases. The JDBC Application Programming Interface has made database programming an important aspect of Java development, particularly where Web applications are concerned. | Chapter 2 Designing a Database In practice you are unlikely to encounter a problem with BCNF since the purpose of assigning a unique ID column rather than relying on supposedly unique legacy data is to prevent problems of this sort. Law firm data Having created the tables required to manage the clients you can move on to setting up the tables for the law firm itself. However after a moment s thought you will probably realize that the tables you have created will handle all the data for the law firm too. Billable items In a time and materials invoicing system there are two kinds of billable items fees and expenses. Fees are charged in a number of different ways the most common of which is hourly. Expenses are simply charged on a unit basis as in the case of photo copies which are billed per page copied. In either case the id of the law firm employee or timekeeper making the charge is provided. The first table required for billable items then is the Timekeeper Table. This table includes a foreign key identifying the individual in the Contacts Table as well as columns for level and hourly rate. The LEDES specification defines the following levels Partner Associate Sx Paralegal Legal Assistant Secretary Clerk Other These levels are best stored in a Lookup Table of billing levels accessed by a foreign key in the Timekeeper Table. Hourly rates too should be stored in a Lookup Table to allow for increases. These two tables contain only an id column and a corresponding level or billing rate so they are not shown here. The resulting Timekeeper Table might look like Table 2-4. Table 2-4 Timekeeper Table id contact_id level_code default_rate_code 1000 2001 1 1 1001 2002 1 2 1002 2007 5 9 -49- Team-Fly Please purchase PDF Split-Merge on to remove this watermark. Chapter 2 Designing a Database Notice how this structure allows for two partners to bill at different rates. It is also intended that the rate code be overridden if the terms of a contract require it. .