Building Data Aware Web Applications with ASP.NET - Part 1
User-Interface Design (Figure 1.1)
The above interface is fully made up of ASP.NET WebForm controls. For example, the code snippet in Listing 1.4 places TextBox and Label controls on to the WebForm. A complete discussion on WebForm controls is beyond the scope of this article. The code behind our User-Interface (HTML Portion) can be downloaded from the link provided at the end of this article.
<form runat = "Server"> <asp:TextBox id = "txtName"> </asp:TextBox>
<asp:Label id = "lblStatus"> </asp:Label> </form>
Simply creating a user-interface won't suffice. You should activate them by proper means like if a user clicks the button, the entered values should have to be saved/stored in a database. In order to achieve this, you should establish a connection to the database (See Listing 1.6). But before this you should call appropriate namespaces as shown in the listing given below:
<%@ Page language = "VB" %> <%@ Import namespace = "System.Data" %> <%@ Import namespace = "System.Data.SQLClient" %>
Sub Page_Load(Src As Object, e As EventArgs) conn = New SqlConnection( _ "Data Source=localhost;User ID=sa;password=;Initial Catalog = Wintergreen") conn.open() End Sub
I assume that you are using the default SQL Server user account namely "sa". If you are using some other ID and password, substitute them in listing 1.6.
The entered inputs will be stored in the table named "Employees" after clicking the button captioned "Save". Hence, the remaining code should be entered inside the button event. Firstly, you should call the stored procedure, which we created earlier and set the CommandType property of SQLCommand object to stored procedure as shown below:
cmdcommand = new sqlcommand("Toregister",conn) cmdcommand.commandtype = commandtype.storedprocedure
Notice that I had created parameterized stored procedure in step 3 above. Hence, you have to refer the parameter name while adding records, using the add method. Moreover, you should also refer the appropriate control name along with it as shown below:
cmdcommand.parameters.add("@name",txtName.text) cmdcommand.parameters.add("@age",txtAge.text) cmdcommand.parameters.add("@email",txtEmail.text) cmdcommand.parameters.add("@address",txtAddress.text) cmdcommand.parameters.add("@username",txtusername.text) cmdcommand.parameters.add("@password",txtPassword.text)
If you have more than one field, simply repeat the above codes by changing the parameter names and the respective control name. The main advantage of using parameterized stored procedure is that you can avoid complex SQL statements in your ASP.NET page and moreover the page also executes faster.
Finally, if the return value from the stored procedure is 0, new user is added to the appropriate table on the database. You can either redirect users to other WebPages or simply display appropriate message in a WebForm control namely Label. Look at the code in the listing below.
If the new user is not added then the appropriate error message should have to be displayed to indicate the status. In our example, if a user feeds in a username, which is already there on the database, the script displays the appropriate message in a Label control. Look at the code snippet shown below:
if cmdcommand.parameters("ReturnValue").value = 0 then lblStatus.text = "Registered Successfully" else lblStatus.text = "Error!, Please try again" end if
The complete code for the button event is shown below in listing 1.10. For your convenience, the code listings have been provided as a ZIP file in the Download section.
cmdcommand = new sqlcommand("Toregister",conn) cmdcommand.commandtype = commandtype.storedprocedure param = cmdcommand.parameters.add("ReturnValue",sqldbtype.int) param.direction = parameterdirection.returnvalue cmdcommand.parameters.add("@name",txtName.text) cmdcommand.parameters.add("@age",txtAge.text) cmdcommand.parameters.add("@email",txtEmail.text) cmdcommand.parameters.add("@address",txtAddress.text) cmdcommand.parameters.add("@username",txtusername.text) cmdcommand.parameters.add("@password",txtPassword.text) cmdcommand.executenonquery() if cmdcommand.parameters("ReturnValue").value = 0 then lblStatus.text = "Registered Successfully" else lblStatus.text = "Error!, Please try again" end if conn.close()
Please note that I have applied Validations to the source file included on the ZIP file and in Live Demo. To test this functionality, click the Save button without entering anything on the textboxes and observe the result. To learn more about Validation Controls refer to my previous article titled "Performing Validations with ASP.NET".
A live demo can bee seen at:
Code DownloadDownload the source code: Part1_codes.zip
Searching and updating of records using DataGrid Control.
About the Author
Anand Narayanaswamy is a Microsoft MVP (Microsoft Most Valuable Professional) who works as a freelance Web/Software developer and technical writer. He runs and maintains learnxpress.com, and provides technical support to users. His areas of interest include Web development, Software development using Visual Basic, and in the design and preparation of courseware, technical articles, and tutorials. He can be reached at firstname.lastname@example.org
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