C#Builder and BDP for .NET ASP.NET Web Forms With DB2 UDB ... · In order to build the application,...

© Copyright IBM Corporation 2003 TrademarksASP.NET Web Forms With DB2 UDB Tables Using C#Builder andBDP for .NET

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ASP.NET Web Forms With DB2 UDB Tables UsingC#Builder and BDP for .NETBob Swart July 17, 2003

This article shows you how to build an application using IBM DB2 UDB tables, C#Builder, andBDP for .NET, and then deploy it as an ASP.NET Web form (with a powerful asp:DataGridcontrol), so users can work with the DB2 UDB tables using a Web browser.

© 2003 International Business Machines Corporation. All rights reserved.

IntroductionIn my first article on using IBM® DB2® Universal DatabaseTM (UDB) with Borland® C#BuilderTM,I showed how the Borland Data Providers (BDP) for .NET could be used to build a connectionto DB2 UDB v8.1 and to use the DB2 SAMPLE tables. In the second article, I examined someindividual Borland Data Provider classes in a bit more detail, especially the design-time editors,and deployed a WinForms application.

In this article, I will show how to build a similar application using DB2 UDB tables, but this time Iwill deploy it as an ASP.NET Web form (with a powerful asp:DataGrid control), so users can workwith the DB2 UDB tables using a Web browser.

Building ASP.NET Web formsFirst, let's first create an ASP.NET Web Form application using C#Builder, then add the connectionto the DB2 UDB SAMPLE tables, and finally configure the user interface using an asp:DataGridcontrol.

Like the earlier articles, I'm using IBM DB2 UDB v8.1 in combination with C#Builder Enterprise onthe Microsoft® .NET Framework 1.1. If you want to create ASP.NET Web forms, you need a Webserver like Microsoft's Internet Information Server (IIS). If you don't have IIS installed, then you canuse the free ASP.NET Cassini Web serverÃ##a sample Web server for which full source code andinstallation instructions can be found in the BDS\1.0\Examples\C#\Cassini directory of C#Builder.

In order to build the application, start C#Builder, and do File > New and enter ASP.NET WebApplication. This will give you the New ASP.NET Application dialog, where you can specify thename of the project (see Figure 1). This name will be used to create a new virtual directory wherethe project files will be placed. It makes sense to use the same name of the virtual directory where

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ASP.NET Web Forms With DB2 UDB Tables Using C#Builder andBDP for .NET

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the ASP.NET Web Form will be deployed (see Deploying your application), but it's not required.I've specified DB2UDB to illustrate that this is an ASP.NET Web form connecting and working withthe DB2 UDB tables.

Figure 1. Select IIS or Cassini as Web server

Note from Figure 1 that you can specify the Web server for which you want to deploy the project(I'm using IIS, but you can select Cassini if you want).

When you click OK, a new C#Builder project is created in the new virtual directory. Instead of aWinForm, however, you now have a WebForm where you can place special Web components.First, however, you should build the connection to the DB2 UDB SAMPLE tables.

Connecting to DB2 UDB

Like last time, you can build the connection to the DB2 UDB SAMPLE tables in a number of ways.You can use the Data Explorer and drag-and-drop a table to the Web Forms. Or you can do it in amore explicit way (which gives you a bit more control over the "magic"), which we'll do here. So,start by dropping a BdpConnection component on the WebForm. Note that it will appear in thenon-visual part of the designer, right under the WebForm.

Select the BdpConnection component and use the Connections Editor verb from the ObjectInspector, or right-click on the BdpConnection component to start the Connections Editor.

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Figure 2. Borland Data Provider: Connections Editor

By default, only four connections are shown: for InterBase, MS SQL Server, Oracle, and DB2.These four are the "sample" connections that I never use myself, although I consider them helpfulexamples. If you have not connected to DB2 UDB before, click Add to create a specific DB2connection to the DB2 SAMPLE database tables.

Figure 3. Add New Connection

Click OK to get back to the Connections Editor, and then specify SAMPLE as the database name,and enter the correct password and username of your DB2 user. You can use the Test buttonto see if the connection properties are set correctly, so you can communicate with the DB2 UDBSAMPLE tables.

Adapting DB2 datasets

Next, drop a BdpDataAdapter component. You can use the verbs Configure Data Adapter orGenerate Typed Dataset, or right-click on the BdpDataAdapter component to select the sameone. You don't want to generate a typed dataset at this time, so select Configure Data Adapter.



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In the Data Adapter Configuration dialog, uncheck the Update, Insert and Delete options, andset the Optimize option. Click on Generate SQL to produce the SQL statement (see Figure 4).Alternately, you can enter a SELECT * from ADMINISTRATOR.EMPLOYEE (yourself) here, of course.

Figure 4. Data Adapter Configuration WizardÃ##Command

Click the DataSet tab, and select New DataSet (see Figure 5). This will automatically create a newDataSet (call it dataSet1) and connect it to the output of the SQL command.



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Figure 5. Data Adapter Configuration WizardÃ##DataSet

Now, click Preview Data to see the preview. Note that you have to click the Refresh button tosee the data again. Also note that you can limit the rows that are requested here. The default isto show the first 100 rows, but for an ASP.NET Web form, you may want to limit it even further, forexample to the first 10 records. So set the value of Rows to fetch to 10, and click Refresh.



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Figure 6. Data Adapter Configuration WizardÃ##preview data

If you close the Data Adapter Configuration wizard, you may notice that the 10 we've specifiedhere has no connection to the value of the MaxRecords property (which is still set to 100). Thismeans that you still get a maximum of 100 records instead of 10, but we'll solve that later in thisarticle (when I get to paging).

Note that in the non-visual designer area of the WebForm, you will see no visual "proof" that thedataSet1 component was added. You need to explicitly right-click in this area of the designer andselect the Line up Icons option in order to refresh the display and show dataSet1 as well (just toverify that nothing is missing).

So far it's been relatively easy, and when it comes to connecting to DB2 you could performalmost the same steps as the last time. But from this point on, things will change compared to theWinForms method.

Controlling the Web

Now it's time to add the ASP.NET Web controls, from the Web Controls category (note that youcan also add components from the HTML Elements category, but these are far less powerful).In order to mimic the application from last time, you need to use an asp:DataGrid component,so drop one on the WebForm. Initially, it will show three columns and five rows (not counting theheader) with "abc" values. But you can bind the asp:DataGrid to the dataSet1 component usingthe DataSource property. And apart from pointing DataSource to dataSet1, you also need to pointthe DataMember property to Table1.



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Figure 7. C#Builder design time overview

Although this will show more columns (for each field, the title is also shown in the columnheaderÃ##obtained from the meta data of the dataset), it will not show the actual data atdesign-time. Also, you still see only five records, and not the 10 specified in the Data AdapterConfiguration Wizard.

To quickly configure the asp:DataGrid a bit, you can click the Auto Format verb (at the lower leftside of Figure 7), which will give you the Auto Format dialog of Figure 8, where you can select aspecial pre-defined scheme (like Professional 1 that I've selected).

Figure 8. DataGrid Auto Format

Before you can compile and run the application to see the actual output, you must first make surethat the data is bound to the asp:DataGrid. This needs to be done at runtime, and the best place



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is in the ASP.NET Page_Load event handler. Double-click on the Web form, which will bring you tothe code editor for the Page_Load event. Write the following code:

private void Page_Load(object sender, System.EventArgs e){ // Put user code to initialize the page here if (!IsPostBack) dataGrid1.DataBind();}

This will make sure that the DataBind method of the asp:DataGrid is only called the firsttime (when you enter the ASP.NET Web Form). All other times (such as when you post backinformation), the asp:DataGrid will already be bound to the data, so there will be no need to callDataBind again. I'll get back to this in a moment.

Running and debugging Web forms

Now, you can save the project, compile it and get ready to run it. The C:\Inetpub\wwwroot directorywill contain a directory called DB2UDB with the project files. This directory has a Bin subdirectorywhere the DB2UDB.dll is placed. From a browser, you can start this project with the URL http://localhost/DB2UDB/WebForm1.aspx (the name of your main form) However, I think it's moreimpressive to be able to debug your code while running, so just press F9 to run the ASP.NETapplication, which will put the IDE in "debug mode" and start the browser on the starting page.

In both cases, the result is the same and can be seen in Figure 9.



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Figure 9. ASP.NET Web Form with DataGrid (showing many records)

Note that you get all records (or at least the first 100Ã##specified by MaxRecords) from theEMPLOYEE table of the DB2 UDB SAMPLE database. This does not look really "professional," Ithink, because the user has to scroll down to see all records (and you won't see the header whenyou're at record 20 or later). Also, if you send many records from the server to the client, thenyou may experience a performance problem and potential bandwidth bottleneck. This can easilyhappen in real-world situations, especially since I've only created a simple SELECT statementwithout a restricting WHERE clause.

Sorting and paging DB2 data

To help solve this problem, you may want to configure the asp:DataGrid options in some moredetail. Close the browser (which will get you back into the C#Builder IDE), select the asp:DataGrid,and this time click the Property Builder verb (lower left side of the screen) to get the DataGridProperties dialog.

The first page can be used to confirm the value for the DataSource and DataMember properties,as well as the Data key field. Note the option for Allow sorting that I've checked as well.



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Figure 10. DataGrid PropertiesÃ##general

In order to allow the sorting to work, you have to do two more things: specify the sort expression,and write some code for the SortCommand.

You can specify the sort expression on the Columns page of the DataGrid Properties Wizard (seeFigure 11).



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Figure 11. DataGrid PropertiesÃ##Columns

For each column, you can set the sort expression (which is typically equal to the field name).This will turn the header of the column into a hyperlink, and if you click on the hyperlink, thenthe SortCommand event handler is executed, passing the specific value of the Sort Expressionas argument. Since this is the actual fieldname, all you have to do to sort the asp:DataGrid is toperform the SQL query against DB2 UDB again, but this time add an ORDER BY clause, followedby the fieldname which is passed as a sort expression.

The C# source code for the SortCommand event handler of the asp:DataGrid is as follows:

private void dataGrid1_SortCommand(object source, System.Web.UI.WebControls.DataGridPageChangedEventArgs e){ Session["OrderBy"] = e.SortExpression; // Order By FieldName bdpDataAdapter1.Active = false; bdpSelectCommand1.CommandText = "SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, " + " WORKDEPT, PHONENO, HIREDATE, JOB, EDLEVEL, SEX, BIRTHDATE, SALARY, " + "BONUS, COMM FROM ADMINISTRATOR.EMPLOYEE"; if ((Session["OrderBy"] != null) && ((string)Session["OrderBy"] != "")) bdpSelectCommand1.CommandText += " ORDER BY " + (string)Session["OrderBy"]; bdpDataAdapter1.Active = true; dataGrid1.DataBind(); label1.Text = this.bdpSelectCommand1.CommandText + " (Page " + (dataGrid1.CurrentPageIndex+1).ToString() + ")";}



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Note that I store the SortExpression in the ASP.NET Session variable, so you can ensure that thesame ordering is used when you get back to the page and have to perform the query again (forexample when you want to jump to another page).

Speaking of going to the next page: you can specify the number of maximum records that theasp:DataGrid should show on a specific page (remember Figure 9, that showed all records inthe gridÃ##not a big deal for this EMPLOYEE table from the DB2 UDB SAMPLE database, buta potential problem when using a bigger table in the real world, of course). I've specified a pagesize of 10 rows. This means that you can get a number of pagesÃ##each with 10 rowsÃ##andyour application has to respond to the right event when the user wants to navigate from one pageto another (using the Next and Previous buttons, as specified, or alternately, the individual pagenumbers).

Figure 12. DataGrid PropertiesÃ##Paging

When the user clicks on one of the navigation buttons, then the PageIndexChanged event of theasp:DataGrid is fired. You can specify that the asp:DataGrid has to start at a specific page usingthe CurrentPageIndex property. Unfortunately, this property has to be set before the data is boundto the asp:DataGrid, otherwise the grid already contains the data. So, you have to bind the dataagain, meaning that you have to de-activate the BdpDataAdapter component, assign the rightvalue to the CommandText property again (ordering the table on the current selected column),then re-activate the BdpDataAdapter and finally bind the data in the asp:DataGrid, as can be seenin the following source code:



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private void dataGrid1_PageIndexChanged(object source, System.Web.UI.WebControls.DataGridPageChangedEventArgs e){ dataGrid1.CurrentPageIndex = e.NewPageIndex; // Go to Page index bdpDataAdapter1.Active = false; bdpSelectCommand1.CommandText = "SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, " + " WORKDEPT, PHONENO, HIREDATE, JOB, EDLEVEL, SEX, BIRTHDATE, SALARY, " + "BONUS, COMM FROM ADMINISTRATOR.EMPLOYEE"; if ((Session["OrderBy"] != null) && ((string)Session["OrderBy"] != "")) bdpSelectCommand1.CommandText += " ORDER BY " + (string)Session["OrderBy"]; bdpDataAdapter1.Active = true; dataGrid1.DataBind(); label1.Text = this.bdpSelectCommand1.CommandText + " (Page " + (dataGrid1.CurrentPageIndex+1).ToString() + ")";}

You can now close the DataGrid Property Builder dialog again. At design-time, the asp:DataGridwill now show hyperlinks in the column headers, and a Next and Previous button in the footer ofthe asp:DataGrid (see Figure 13).

Figure 13. C#Builder HTML design time overview

There's one more thing that you may want to do: the first time the ASP.NET Web Form is created(in the Page_Load event handler), you may want to clear the OrderBy Session variable, and set avalue to the asp:label control (which I mainly use for debugging purposes, by the way, but which isuseful to show the SQL statement that was executed and the page number you're currently lookingat).



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private void Page_Load(object sender, System.EventArgs e){ // Put user code to initialize the page here if (!IsPostBack) { Session["OrderBy"] = ""; dataGrid1.DataBind(); label1.Text = this.bdpSelectCommand1.CommandText + " (Page " + (dataGrid1.CurrentPageIndex+1).ToString() + ")"; }}

The result of compiling and running the ASP.NET application from the C#Builder IDE can beseen in Figure 14. Note that the initial SQL statement is performed (equivalent to select * fromemployee) without an order by clause, and starting at the first page.

Figure 14. Final ASP.NET output (initial page)

We can click the > button to go to the next page, as shown in Figure 15.



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Figure 15. Final ASP.NET Output (second page)

Now you can click the FIRSTNME column to sort the asp:DataGrid by this field, as shown inFigure 16. Note that you stay at the second page, but this time the second page of the SQL querythat performs the order by for the FIRSTNME field.



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Figure 16. Final ASP.NET output (sorted by firstnme)

Optionally, you may want to reset the CurrentPageIndex property of the asp:DataGrid in theSortCommand event handler, so you always get back to the first page when you want to re-sort thedata in the grid. You can do this by adding the following line as first line of the SortCommand eventhandler:

dataGrid1.CurrentPageIndex = 0; // first page (start to count at 0)

Deploying your applicationWhen it's time to deploy your application, you will likely want to deploy it on a Web server whereyou can access the DB2 UDB (so the DB2 client needs to be installed), where typically C#Builderwould not be installed. This means that several files of your application must move to the finalWeb server machine. For the current demo, that means that you need to deploy the web.config,global.asax (which wasn't modified anyway), and the WebForm1.aspx (containing the HTMLfor the ASP.NET Web form). And, of course, you need to deploy the DB2UDB.dll from the Binsubdirectory. This file contains the compiled Code Behind part of the ASP.NET Web Form.

Apart from those (example) project-specific files, you also need to deploy the Borland DataProvider files. Starting with the bdpdb2.dll, which has to be placed in the path or, as is usuallyeasier, in the same Bin directory where the DB2UDB.dll is deployed. That way, the ASP.NET WebForm will automatically find the dbpdb2.dll.



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The three BDP assembliesÃ##Borland.Data.Provider.dll, Borland.Data.Common.dll, andBorland.Data.Db2.dllÃ##can be placed in the same directory as the Code Behind file, but in thiscase it's better to deploy them in the Global Assembly Cache using gacutil. In the latter case, theywill be shared on your .NET Web server and can be used by other (ASP).NET applications as well.

Conclusion

In this article, I've shown that DB2 UDB is a powerful DBMS to build ASP.NET Web forms, wherethe data from DB2 can be accessed using the Borland Data Providers for .NET. Connecting toDB2 UDB using the Borland Data Providers works in a uniform way, whether you're building GUIWinForms (as in my last article) or ASP.NET Web forms (this time).

Borland RAD Tools and DB2 UDB can connect on .NET, native Win32 as well as Linux, andwith the flexible connection between the two, you can build GUI applications as well as Webapplications that can be used to work on data from the DB2 UDB tables.

Disclaimer

This article contains sample code. IBM grants you ("Licensee") a non-exclusive, royalty free,license to use this sample code. However, the sample code is provided as-is and without anywarranties, whether EXPRESS OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OFMERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. IBMAND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEETHAT RESULT FROM YOUR USE OF THE SOFTWARE. IN NO EVENT WILL IBM OR ITSLICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVERCAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OFOR INABILITY TO USE SOFTWARE, EVEN IF IBM HAS BEEN ADVISED OF THE POSSIBILITYOF SUCH DAMAGES.

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