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注意事項(xiàng)
How would you accomplish this task?
你該如何完成這項(xiàng)任務(wù)？
First ,you would probably go through the customer files in alphabetical order, foler by folder.
第一，你可能要按字母順序仔細(xì)檢查顧客文件，一個(gè)文件夾接著一個(gè)文件夾去查。
You would examine each invoice in the folders to determine if the amount is in excess of $2,500 and remove and copy each invoice that meets the criterion.
你還要查看文件夾內(nèi)的每個(gè)發(fā)貨票，以便確定其數(shù)額是否超過2500美元，對(duì)于滿足要求的每個(gè)發(fā)貨票要取出并加以復(fù)印。
You would then have to refill the copies you removed and risk misfiling them
然后你還必須把取出的部分重新歸檔
When you had examined all the customer folders and copied all the appropriate invoices.
當(dāng)你檢查了全部顧客文件夾并復(fù)印了全部需要復(fù)印的發(fā)貨票，
you would then review the copies and put together your report.
你還要重新檢查并且整理好
Imagine how much time this would take.
可以設(shè)想一下，做這些工作要花去多少時(shí)間。
If there are a lot of customers, you would need to spend hours if not days.
如果有大量顧客時(shí)，即使無需花好幾天，也需要花好幾個(gè)小時(shí)吧。
Now let's look at the situation in a different way.
現(xiàn)在我們用另一種方式來研究這個(gè)問題。
The environment is the same , except that ,instead of file cabinets.
環(huán)境情況不變以，只是取代文件柜的是，
you have a microcomputer or a terminal and DBMS software that has access to a customer database file as shown in the following .
你有了一臺(tái)微型機(jī)或一臺(tái)終端，以及可以訪問顧客數(shù)據(jù)庫的DBMS軟件，這個(gè)顧客數(shù)據(jù)庫文件如下面所示。
In this file a row of customer data is referred to as a record, and an individual piece of data within a record ,such as a name ,is referred to as a field.
在文件中，每一排顧客數(shù)據(jù)稱為一個(gè)記錄，記錄內(nèi)的單獨(dú)數(shù)據(jù)段（如姓名）則稱為一個(gè)字段。
To get the invoice data you need, you would do something like this.
為了獲得你所需的發(fā)貨票數(shù)據(jù)，你總要做如下一些事情。
Turn on the computer and the printer.
啟動(dòng)計(jì)算機(jī)及打印機(jī)。
start up the DBMS software
啟動(dòng)DBMS軟件。
Give the command to open up the customer database file stored on your disk ,which is similar in concept to manually opening up the customer file in a filing cabinet.
發(fā)出命令，以便“打開”存儲(chǔ)在磁盤中的顧客數(shù)據(jù)庫文件，從概念上講“打開”既類似于用手打開文件柜中的顧客文件。
Give the command to search all the records in the database file and display copies of the records that meet your criterion.
發(fā)出命令，以便搜索查找數(shù)據(jù)庫文件中的全部記錄，并顯示合乎要求的記錄內(nèi)容。
that is the names of people with unpaid invoices greater than $2,500.
（即，發(fā)貨票總金額超過2500元未付款人的姓名）。
If you were using dBASE IV , a popular microcomputer DBMS ,the command would look something like.
如果你一直使用的是Dbase 1v（一種在微機(jī)上使用的著名的DBMS），則命令會(huì)是：
If you were using SQL( Structured Query Language) the command would look like this.
如果你一直使用SQL（結(jié)構(gòu)化查詢語言），則命令會(huì)是：
In response to this command ,all the records in the file that have an invoice amount greater than $2,500 will be listed on the screen.
作為這些命令的回答，在文件的全部記錄中，凡是多于2500元的發(fā)貨票，均將在屏幕上顯示出來。
The SQL command would also sort the listing into order by name.
（SQL命令將挑選的發(fā)貨票按姓名進(jìn)行排序）。
This whole procedure would take perhaps only five minutes or less.
全部過程可能只需要5分鐘，甚至更少。
