【正文】 se to be accessed the same way. This is called Universal Data Access, or UDA. Understanding what UDA means is not as simple as understanding to use it. The reason for this is that UDA is a set of rules and access methods that must be followed by any pany that is creating a database access method to be used. This allows you, the programmer, to access any database the same way But what is UDA? Universal Data Access is a platform, applications and tools concept that Microsoft has developed that defines and delivers the standards for all future application development. Using UDA standards will provide high performance access to many types of data and information that reside on multiple platforms, and a programming interface that will work with almost any tool or language using the skills that developers already have. This is acplished by using Microsoft’s Data Access Components (MDAC), as well as an integrated set of technologies, which include ActiveX Data Components (ADO), OLE DB, and Open Database Connectivity (ODBC). The benefits of using these standards include the following: High performance access to data – Provides the ability to scale any application or ponent to support concurrently connected users without losing performance。 Oracle。Search for a particular name。 Provide easy ways to select static information (such as state names)。Delete。 Other applications provide users with a way to choose from a list of options that would modify the applications standard reports. This way, you can design and create a few standard reports that users could then modify to print many different versions。 Some display a dialog box listing each available report. Users select the one they want and other click a button to continue。 Previous (entry)。Enable easy maintenance of the application. Now, if this list seems simplistic, it is! You would then expand each item in this list until you’re satisfied with the result. Let’s expand each of the preceding tasks and add a more detail to the definition. Keeping Names and Addresses What do you really mean when you say ― Keep names and addresses?‖ It usually means that you want to keep track of the standard information found in any standard telephone book you look at. The first step in defining all the minitasks required for this topic is to list the data elements you want to put in the database. Table 1 lists the data elements that you can use for this type of application. Name Type First Name String Last Name String Spouse Name String Child Name String Address String City String State String ZIP Integer EMail Address String Phone Long Birth Date Date Notes String Table 1: Data Elements That Can Be Included In The Application Database. This list is pretty straight forward, but look more closely at it. It has elements such as phone numbers and birth date. Can a person not have more than one phone number? Yes! Or, if you’re allowing users to enter the names of the person’s spouse and children, you could have more than one birth date to enter. When the tables for this database are created, you’ll need to design the capability to handle copies of these types of elements. How do you want users to see the information? This section of the application will require the following forms: Book entry form: and Detailed Entry display. Although only two forms are involved with the data entry and display, each form performs quite a bit of processing. The first form gives users an easy way of entering information. Depending on how fancy you want to get, you could create a form that uses many of the more advanced Visual Basic controls. Also, you can see that the form is split in two with the TabStrip control to make unique areas for business and personal information for that entry. Now, what are the tasks that this form must perform when a new entry is added? This list is fairly standard for most database applications: Validate the dates entered: Edit the phone numbers for the correct amount of digits: Verify that this person is not already in the database。Keep names and addresses。 and and 就 Microsoft Access 97 而論，數(shù)據(jù)庫文件不能超過 1GB(千兆字節(jié) )。 為了防止這類問題的發(fā)生，確定適合你應(yīng)用程序功能 (函數(shù)和特征 )的目錄和繼續(xù)堅持做到底。但是如果某些事情在他們的計算機(jī)上出錯怎么辦還有他 們丟失了數(shù)據(jù)庫文件，還是他們不小心刪除額文件？ 如果這些不可想象的意外發(fā)生，你的軟件必須允許用戶創(chuàng)建數(shù)據(jù)庫文件的備份的文件，他們可以簡單的從他們的備份文件中恢復(fù)數(shù)據(jù)。 考慮到不同用戶 很多數(shù)據(jù)庫應(yīng)用軟件都支持復(fù)雜的數(shù)據(jù)庫復(fù)制操作。不同的應(yīng)用軟件中提供了不同的方法： 注意那一組選擇按鈕允許用戶根據(jù)特定的字段進(jìn)行搜索，同時空白處允許用戶輸入合法的關(guān)鍵詞 進(jìn)行搜索。但是在你使用瀏覽器風(fēng)格的界面時，它好像不能根據(jù)一個人的名來查詢?，F(xiàn)在的上課也是在這基礎(chǔ)上做稍微的修改。你也可以根據(jù)你的喜歡，用 Visual Basic 的很多高級控件來建立一個表格。允許不同的用戶 在你決定你的程序?qū)⒁峁┠男┕δ苤?，你必須決定你的應(yīng)用程序使用什么樣的界面。 選擇任務(wù) 闡明應(yīng)用程序的任務(wù)同時也確定它的復(fù)雜性。 數(shù)據(jù)庫設(shè)計在 VB 中應(yīng)用 2 作者 ： Errol Booysens 難度 ：初學(xué)者到中等 開始初步設(shè)計 開發(fā)一個應(yīng)用程序很像建造一幢房子，為一所建造得好的房子， 你需要一張藍(lán)圖跟隨， 但是建立一張好藍(lán)圖，你需要知道誰將要住在房子和他們的生活方式怎么樣。 大多數(shù)大公司使用 (雖然這是不說其它不可以 ) 的下列數(shù)據(jù)庫系統(tǒng)一： 一些有事業(yè)心青少年已經(jīng)創(chuàng)建幫助他們跟蹤棒球卡片或者錄像帶的數(shù)據(jù)庫應(yīng)用。 在 Visual Basic 的以前的開發(fā)過程中， 你需要可供選擇 DAO(本地 )存取數(shù)據(jù)的方法或者 RDO(遠(yuǎn)程 ) 存取數(shù)據(jù)。這被叫為通用數(shù)據(jù)存取或者 UDA。MS SQL Server 簡單提一下 所有這些數(shù)據(jù)庫能在一臺獨(dú)立計算機(jī)上運(yùn)行并且允許你創(chuàng)造你的應(yīng)用程序的復(fù)雜的數(shù)據(jù)庫。 什么是數(shù)據(jù)庫？ 數(shù)據(jù)庫包含很多不同目標(biāo)使用一同允許你應(yīng)用快和有效率的參數(shù)的系統(tǒng)。 什么時候使用 Visual Basic，你可以選擇的