外文翻譯--visual basic數據庫連接介紹指南

1、<p>　　Visual Basic Database ConnectivityAn Introductory Guide</p><p>　　1. Create the VB .Net Application</p><p>　　Create a blank VB .Net solution in your account and add a newproject to the

2、 solution. This should automatically create a blankform for you. Also copy the Authors.mdb database file from the COMP315 library folder into your account. </p><p>　　2. Using Data Adapters and Data Sets</

3、p><p>　　To manipulate data in an access database you need to use a data adapter to connect to the database and a data set to manipulate the data.</p><p>　　3. Creating the Data Adapter</p>&l

4、t;p>　　To create a Data Adapter that contains the SQL statement you want to populate the dataset with, do the following: Click on the 'Data' tab in the tool box and then double click on the OleDbDataAdapter con

5、trol to add it into the form. The Data Adapter Configuration Wizard will automatically appear to help you configure the Data Adapter. </p><p>　　Figure 1. Location of the Data tab in the toolbox.</p>&

6、lt;p>　　Click on Next> to move to the next screen. Now the Data connection to use box should be blank so click on the New Connection button to configure the new connection. Select the Provider tab and then select Mi

7、crosoft Jet 4.0 OLE DB Provider and then click on Next>.</p><p>　　In section 1 where it asks for the database to use, click on the '…' button and then navigate to and select the Authors.mdb databa

8、se and click on the Open button.. Leave section 2 as it is. Your screen should look similar to this: </p><p>　　Figure 2. Completed Data Link Properties.</p><p>　　Click on the Test Connection but

9、ton and you should get a message saying 'Test Connection Succeeded'. If you don’t then check you have followed the instructions above. Click on OK to return to the Data Adapter Wizard and then click on the Next&g

10、t; button.</p><p>　　Make sure that Use SQL statements is selected and then click on the Next> button.</p><p>　　In the large text box type in the following SQL statement:</p><p>　

11、　Select * from authors</p><p>　　Then click on the Next> button and then the Finish button. You may be asked if you want to include a password in the connection string, so just click on Don’t Include Passw

12、ord. You should now see a new Adapter object and a new Connection object.</p><p>　　4. Creating the Dataset</p><p>　　The next step is to create a Dataset class based on the query you specified ab

13、ove. Make sure that your Data Adapter object is selected and at the bottom of the properties pane click on the Generate Dataset… link and you should see the window below appear.</p><p>　　Figure 3. The Genera

14、te Dataset window.</p><p>　　Select 'New' data set rather than 'Existing' data set and give it the name dsAuthors and make sure the 'Add This Dataset to the Designer' option is selecte

15、d. Click on the OK button to generate the authors dataset and you should see the Dataset object 'dsAuthors1' added to your project.</p><p>　　5. Adding a Data Grid Control</p><p>　　Now yo

16、u need to add a data grid control to your form. Do this by selecting the Windows Forms tab in the tool box and then double click on the Data Grid control in the toolbox to add it to your form. Move it around and make it

17、bigger. </p><p>　　Go to the 'DataSource' property of the data grid and click on the down arrow and select dsAuthors1. For the 'DataMember' property select the Authors option. This has effecti

18、vely bound the data grid control to your authors dataset.</p><p>　　6. Filling the Data Set With Information</p><p>　　Now run the application, what do you see? There is no data in the data grid!

19、What you need to do is to fill the dataset with the appropriate data. Stop the application running and then add a button and name it appropriately and give it the caption Display Data. Now create a click event procedure

20、for that button and in the click event procedure type in the following:</p><p>　　DsAuthors1.Clear()</p><p>　　OleDbDataAdapter1.Fill(DsAuthors1, "Authors")</p><p>　　The fir

21、st statement clears the dataset of previous information and the second statement uses the fill method of the data adapter to get the new data from the database. The first parameter of the Fill method is the dataset to fi

22、ll and the second parameter is the name of the table that you used when you set the DataMember property of the data grid control.</p><p>　　Now run your application again and when you click on your button you

23、 should see all the author information appear. If you click on the column names it will sort the data on that column. Pretty cool eh!</p><p>　　7. Updating Changes Made in the Data Grid</p><p>　　

24、You can also change the information by clicking on a cell and then changing the data. Sort by last name and change the surname of 'Ann Dull' to 'Ann Exciting'. Close the application and run it again. What

25、 happened to the change you made to the surname? You should find that the surname is still 'Dull'. The reason why, is that the change was made to the data set but not to the database. The data set is like a tempo

26、rary table in the computers memory so any changes to it doesn't affect the data in t</p><p>　　You need to use the Update method of the Data Adapter to save any changes made to the dataset to the database

27、. To do this first add another button the form and give it the caption Save and then create a click event procedure for the button. Then type in the following statement in the click</p><p>　　event procedure:

28、</p><p>　　OleDbDataAdapter1.Update(DsAuthors1)</p><p>　　This statement calls the Update method of the Data Adapter and you need to specify the dataset to update as the parameter.</p><

29、p>　　Now run the application again and change the surname again and then click on the Save button. Close the application and run it again and you should see the change has been made to the database now. Try adding a ne

30、w row at thee bottom of the data grid using your name and make up data for the other attributes. Be careful to use the correct format for data otherwise you may get an error if the format of what you enter does not match

31、. Don’t forget to click on 'Save' to make the change to the databas</p><p>　　8. Deleting Information using the Data Grid</p><p>　　Deleting a row from the table is also very easy. Just cl

32、ick in the area at the very beginning of the row before the first column to highlight the entire row. Now press the Delete key on your keyboard to delete the row and click on the Save button to save your changes to the d

33、atabase. In fact you don’t need to click on save after every change, just make all the changes to want to make and then click on the Save button at the very end and all changes will be saved to the database. Too Easy!<

34、;/p><p>　　9. Filtering the Data Set</p><p>　　Now lets try filtering the data so that we only see the data we are interested in. We will use a combo box to allow the user to enter a value for the St

35、ate and then only show authors living in that state in the data grid. We will need a second data adapter to retrieve back all of the states in the database. Add another data adapter like you did for the first one and you

36、 should find that the database connection you used for the first one is already present so use that. When you type in your SQL s</p><p>　　Select distinct state from authors</p><p>　　Then click o

37、n the Advanced Options button and clear the option for 'Generate Insert, Update and Delete statements' as shown below:</p><p>　　Figure 4. Configuring the advanced options.</p><p>　　Then

38、click on Next> and Finish to create the second data adapter. At this point it would be better to rename this adapter so it easy to remember what the adapter is for so select the second data adapter object and in the p

39、roperties pane change the name to sdaState. Now create a second data set with the name dsState from your sdaState data adapter.</p><p>　　10.Filling a Combo Box With Data From a Data Set</p><p>　

40、　You are ready to create your combo box now so double click on the combo box control in the tool box to add it to your project and give it the name cboStates. Set the 'DataSource' property to dsState1 and the 

41、9;DisplayMember' property to Authors.State, you will need to click the drop down arrow and then expand the Authors option to display the list of columns you can use. Set the 'DropDownStyle' property to DropDo

42、wnList and set the 'ValueMember' property of the combo box to Authors.State. This is </p><p>　　So we have the data set ready and the combo box ready, the last thing we need to do us to populate the c

43、ombo box automatically when the application runs. To do this we need to create a Form Load event procedure which will execute the statements in the procedure when the form is loaded. Just double click on an empty area of

44、 the form to create the form load event procedure</p><p>　　and then add the following statements: </p><p>　　DsState1.Clear()</p><p>　　sdaState.Fill(DsState1, "authors")<

45、;/p><p>　　Now run your application and you should see in the dropdown list of the combo box all of the states in the authors table.</p><p>　　Visual Basic數據庫連接介紹指南</p><p>　　1.創(chuàng)造的VB.NET應

46、用</p><p>　　創(chuàng)建一個空白的VB.NET的解決方案，在您的帳戶，并添加新工程來解決這個問題。這應該會自動創(chuàng)建一個空表給你。從comp315 Library文件夾到你的帳戶，還復制authors.mdb數據庫文件。</p><p>　　2.利用數據適配器和數據集</p><p>　　操縱數據在一個Access數據庫上，你需要使用一個數據適配器連接到數據庫和數

47、據集，以操縱數據。</p><p>　　3.創(chuàng)建數據適配器 </p><p>　　創(chuàng)建一個數據適配器包含SQL語句，你要填充數據集，做好以下工作：點擊'數據'標簽中的工具箱，然后雙擊該數據庫連接數據適配器控制它添加到表單。數據適配器配置向導會自動出現，以幫助您配置數據適配器。 </p><p>　　圖1.位置的數據統計表，在工具箱。</p&g

48、t;<p>　　點擊未來>移動到下一個屏幕?，F在，數據連接使用票房應該空白，使點擊這個新的連接按鈕來配置新的連接。選擇供應商標簽，然后選擇微軟提供的Jet 4.0 OLE DB，然后點擊下一步>。</p><p>　　在第1條中，為所要求的數據庫來使用，點擊' … … '按鈕，然后瀏覽并選擇authors.mdb數據庫，并點擊打開按鈕..離開第2條，因為它是。你的屏幕應該

49、看看類似這樣的：   </p><p>　　圖2.完成數據鏈路性能。</p><p>　　點擊測試連接按鈕，你應該看到一條信息，說'測試連接成功' 。如果你不那么清楚那你跟隨到以上指示。點擊OK返回到數據適配器向導，然后按一下該下一步> "按鈕。</p><p>　　確保使用SQL語句是選定，然后按一下下一步> &qu

50、ot;按鈕。 </p><p>　　在大文本框中鍵入以下SQL語句： </p><p>　　Select * from authors</p><p>　　然后按一下下一步> "按鈕，然后點擊完成按鈕。你可能會問，在連接字符串如果你想包含一個密碼，所以只要點擊不包括密碼。你現在應該看到一個新的適配器對象和一個新的Connection對象。 </

51、p><p><b>　　4.創(chuàng)建數據集</b></p><p>　　下一步該是創(chuàng)建基于查詢的數據集，您指定以上查詢。確保你的數據適配器對象選定，并在底部的屬性面板中點擊該能產生數據集的環(huán)節(jié)，你應該看到下面窗口出現。</p><p>　　圖3.該數據集生成窗口。</p><p>　　選擇'新'的數據集，而不是現

52、有的數據集，并賦予它的名字dsauthors并確保'添加此套數據，以選中設計師該選項。點擊OK按鈕生成數據集的作者，你應該看到數據集對象' dsauthors1 '添加到您的項目。</p><p>　　5.添加一個數據網格控制</p><p>　　現在，你需要添加一個數據網格控制到表單中。做到這一點可以通過選擇窗口表格標簽中的工具箱，然后雙擊該數據網格控制在工具箱以

53、便將它添加到表單中。移到表單，并使它有更大發(fā)展。</p><p>　　除去數據源參數的安全數據網格，并點擊向下的箭頭，并選擇dsauthors1 。為選擇 數據成員參數專責的作者。這有力地約束數據網格控制你的作者數據。</p><p><b>　　6.填充數據集信息</b></p><p>　　現在運行的應用，你怎么看？在數據網格有沒有數據！你

54、需要做的是填補適當的數據。停止運行的應用，然后添加一個按鈕和得當名稱，并賦予它屏幕顯示數據?，F在創(chuàng)造一個點擊事件的程序，那個按鈕，并在點擊事件程序類型，在以下方面：</p><p>　　DsAuthors1.Clear()</p><p>　　OleDbDataAdapter1.Fill(DsAuthors1, "Authors")</p><p&g

55、t;　　第一項聲明擦亮了數據集的前信息和第二次聲明，使用充填采礦法的數據適配器，從資料庫中以獲取新的資料。第一個參數的填寫方法是將數據填補,第二個參數是表的名稱，你用的時候，你定數據成員參數的安全數據網格控制。</p><p>　　現在運行你的應用程序，再當你點擊你的按鈕，你應該可以看到所有的作者信息出現。如果你點擊這個欄目的名字，將上欄進行數據排序。蠻不錯嗯！</p><p>　　7.在

56、數據網格更新的變化</p><p>　　您也可以通過點擊一個基本存儲單元更改信息，然后再改變數據。按照姓名排序和改變姓名 'Ann Dull' 到 'Ann Exciting'。關閉該應用程序并運行它。所發(fā)生的事情，以改變你的姓？你應該發(fā)現姓仍然是'枯燥'。原因是，記錄改變以數據集，而不是數據庫。該數據集該像一個臨時表，在電腦記憶體里，所以它任何改變并不影響數據庫中

57、的實際表中的Access數據庫。</p><p>　　你需要使用更新的方法數據適配器，以節(jié)省所做的任何更改數據集到數據庫。要做到這一點首先放入另一個按鈕的布局，并賦予它字幕保存，然后創(chuàng)造一個點擊事件的程序按鈕。然后鍵入以下聲明中點擊活動程序：</p><p>　　oledbdataadapter1.update（dsauthors1）</p><p>　　這項聲明呼

58、吁更新方法的數據適配器，你需要指定數據集，以更新作為參數。</p><p>　　現在運行的應用，并再次改變姓氏，然后再次點擊保存按鈕。關閉該應用程序并讓它再次運行，你應該看到它已經向數據庫的變化。嘗試加入一個新的排在禰底部的數據網格用你的名字和彌補數據，為其它屬性。注意為數據使用正確的格式，否則，如果格式要求是什么，你輸入不匹配，你可能會得到一個錯誤。不要忘了點擊'保存'，以改變數據庫。</

59、p><p>　　8.刪除信息使用數據網格</p><p>　　從表中刪去一排也很容易。只需按一下該地區(qū)在開始的前行的第一欄，以突出整個排。現在按下刪除鍵，即可刪除該行并點擊保存按鈕保存更改到數據庫。事實上，你不用每一次變化后都點擊保存，也希望只是盡一切改變，然后點擊保存按鈕，在最后一刻，所有的改變將被保存到數據庫。太容易了！</p><p><b>　　9.過

60、濾數據集</b></p><p>　　現在試圖過濾數據，我們感興趣的是讓我們看到的只是數據，我們將使用一個組合框，讓用戶輸入一個值的狀態(tài)，然后，只能說明作者在數據網格的該狀態(tài)。我們還需要有第二個數據適配器取回回所有的狀態(tài)在數據庫中。加上另一個數據適配器一樣，你做了第一次，你應該發(fā)現數據庫連接，你用第一種是已經存在，所以利用這一點。當你輸入你的SQL語句，輸入以下內容：</p><p

61、>　　選擇從表沖不同的狀態(tài)，</p><p>　　然后點擊高級選項按鈕，并明確了選擇“生成插入，更新和刪除報表” ，如下所示：</p><p>　　圖4.配置高級選項。</p><p>　　然后點擊下一步> ，并整理，以創(chuàng)造第二個數據適配器。在這一點上，為這個適配器將更好地改名，所以容易被記住的適配器，所以選擇第二個數據適配器對象，并在屬性面板中的名稱更

62、改為sdastate。現在，創(chuàng)建第二個數據集，該人的姓名dsstate 在你的sdastate數據適配器中。</p><p>　　10.從一個數據集填補了組合框中的數據</p><p>　　你已準備好，創(chuàng)造你的組合框中，現在這么在工具箱控制雙擊該組合框中以便將它添加到你的項目，并賦予它的名字cbostates 。定'的DataSource '參數dsstate1和'

63、 displaymember '參數authors.state ，你將需要點擊下拉箭頭，然后再擴大作者選項顯示名單欄目，你可以使用。定' dropdownstyle '參數dropdownlist ，并設定' valuemember '參數的安全組合框中，以authors.state 。這該是用這樣的實際價值，是用來當一個項目是在選定的名單中。</p><p>　　因此，我

64、們有數據集的準備，并在組合框中準備好，最后我們需要做的，我們力求普及組合框中時自動運行的應用。要做到這一點，我們需要創(chuàng)造一種形式負荷事件的程序，將執(zhí)行報表，在程序當形式加載。剛剛雙擊一個空白區(qū)的事件創(chuàng)造了形式負荷事件程序然后添加以下聲明：</p><p>　　DsState1.Clear()</p><p>　　sdaState.Fill(DsState1, "authors&q