【導(dǎo)讀】題庫管理和試卷生成系統(tǒng)是為教師方便且快速出試卷而開發(fā)的?，F(xiàn)在的試題動(dòng)不動(dòng)就是上千道。之多，連練習(xí)書都是厚厚的一沓。想從里面挑一份好的試卷實(shí)在是不容易。簡直就沒有效率可言。輸入題庫，到要出試卷的時(shí)候你只要輕松的點(diǎn)幾下鼠標(biāo)就可生成一份高質(zhì)量的試卷了。試卷，要么到龐大的題庫里一道一道的把題找出來，或是從幾本相關(guān)的書里把題一道一道挑出來。又費(fèi)力，而且很難保證試題的覆蓋面和把握好試卷的難度。為了達(dá)到預(yù)期的目標(biāo)我們最終選擇了DataReport做為本軟件的終端輸出。有控件的改進(jìn)和VB編程的研究的基礎(chǔ)上開發(fā)的。

　　

【正文】 mdArgs() As String) As Integer About designing a database Good database design ensures that your database is easy to maintain. You store data in tables and each table contains data about only one subject, such as customers. Therefore, you update a particular piece of data, such as an address, in just one place and that change automatically appears throughout the database. A welldesigned database usually contains different types of queries that show the information you need. A query might show a subset of data, such as all customers in London, or binations of data from different tables, such as order information bined with customer information. The results you want from your database— the forms and data access pages (data access page: A Web page, published from Access, that has a connection to a database. In a data access page, you can view, add to, edit, and manipulate the data stored in the database. A page can also include data from other sources, such as Excel.) you want to use, and the reports you want to print— don39。t necessarily provide clues about how you should structure the tables in your database, because you often base forms, reports, and data access pages on queries instead of tables. Before you use Microsoft Access to actually build tables, queries, forms, and other objects, it39。s a good idea to sketch out and rework your design on paper first. You can also examine welldesigned databases similar to the one you are designing, or you can open the Northwind sample database and then open the Relationships window (Relationships window: A window in which you view, create, and modify relationships between tables and queries.) to examine its design. Follow these basic steps when designing your database. Determine the purpose of your database The first step in designing a database is to determine its purpose and how it39。s to be used: ? Talk to people who will use the database. Brainstorm about the questions you and they would like the database to answer. ? Sketch out the reports you39。d like the database to produce. ? Gather the forms you currently use to record your data. As you determine the purpose of your database, a list of information you want from the database will begin to emerge. From that, you can determine what facts you need to store in the database and what subject each fact 陜西理工學(xué)院畢業(yè)設(shè)計(jì) belongs to. These facts correspond to the fields (columns) in your database, and the subjects that those facts belong to correspond to the tables. Determine the fields you need in the database Each field is a fact about a particular subject. For example, you might need to store the following facts about your customers: pany name, address, city, state, and phone number. You need to create a separate field for each of these facts. When determining which fields you need, keep these design principles in mind: ? Include all of the information you will need. ? Store information in the smallest logical parts. For example, employee names are often split into two fields, FirstName and LastName, so that it39。s easy to sort data by LastName. ? Don39。t create fields for data that consists of lists of multiple items. For example, in a Suppliers table, if you create a Products field that contains a maseparated list of each product you receive from the supplier, it will be more difficult to find only the suppliers that provide a particular product. ? Don39。t include derived or calculated data (data that is the result of an expression (expression: Any bination of mathematical or logical operators, constants, functions, and names of fields, controls, and properties that evaluates to a single value. Expressions can perform calculations, manipulate characters, or test data.)). For example, if you have a UnitPrice field and a Quantity field, don39。t create an additional field that multiplies the values in these two fields. ? Don39。t create fields that are similar to each other. For example, in a Suppliers table, if you create the fields Product1, Product2, and Product3, it will be more difficult to find all suppliers who provide a particular product. Also, you will have to change the design of your database if a supplier provides more than three products. You need only one field for products if you put that field in the Products table instead of in the Suppliers table. Determine the tables you need in the database Each table should contain information about one subject. Your list of fields will provide clues to the tables you need. For example, if you have a HireDate field, its subject is an employee, so it belongs in the Employees table. You might have a table for Customers, a table for Products, and a table for Orders. Determine which table each field belongs to When you decide which table each field belongs to, keep these design principles in mind: ? Add the field to only one table. ? Don39。t add the field to a table if it will result in the same information appearing in multiple records in that table. If you determine that a field in a table will contain a lot of duplicate information, that field is probably in the wrong table. For example, if you put the field containing the address of a customer in the Orders table, that information will probably be repeated in more than one record, because the customer will probably place more than one order. However, if you put the address field in the Customers table, it will appear only once. In this respect, a table in a Microsoft Access database (Microsoft Access database: A collection of data and objects (such as tables, queries, or forms) that is related to a particular topic or purpose. The Microsoft Jet database engine manages the data.) differs from a table in a flat file database such as a spreadsheet. When each piece of informat