Simple Data Binding Complex Data Binding Binding Data Grids Binding Standard Web Server Controls Navigating in Datasets Controls Designed for Use with Databases Using Data Grids in Web Applications Using Data Lists in Web Applications Using Repeaters in Web Applications Immediate Solutions: Using the BaseDataList Class Using the DataGrid Class Creating a Data Grid Binding Standard Controls Navigating in Datasets Using the DataList Class Creating a Data List Using the Repeater Class Creating Repeaters Using Data Readers Creating Master/Detail Web Forms Using XML-Format Databases Directly in the Internet Explorer
In this chapter, we'll take a look at using databases in Web applications. The actual work you do with databases in Web applications is back on the server in Visual Basic code, of course, even if the database is on another Web server somewhere, so you still use the data connection, data adapter, and dataset objects that we've been using up to now. This means that the behind-the-scenes code that works with databases is going to be the same here as in previous chapters. We'll still use data adapters to fill datasets, and use connection objects to connect to databases, for example.
However, we're dealing with a different user interface here—Web forms. Web forms are displayed in the browser, which means your application doesn't have direct access to Visual Basic without being sent back to the server, and that's going to affect the way we do things here. The difference between working with data in Windows forms and Web forms is largely a matter of differences in data binding and in the types of controls you can use, as we'll see here.
Because there's no direct connection maintained between a dataset and controls bound to that dataset, you're responsible for refreshing the data binding to controls in a Web form each time the page loads. In a Windows application, you don't need to do that; when the page loads, all you have to do is to clear the dataset and use a data adapter to fill a dataset, and the data bindings in the form are automatically updated:
In Web applications, the process is similar, but now you also have to explicitly run the DataBind method of any controls bound to the dataset, like this:
Private Sub Page_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load DataSet11.Clear() OleDbDataAdapter1.Fill(DataSet11) TextBox1.DataBind() End Sub
This refreshes the data in the bound control each time the page loads, which you don't have to do in Windows applications, because there, that connection is "live." Besides having to use DataBind to maintain data bindings, and aside from the obvious fact that Web server controls have fewer properties than Windows forms controls, working with databases in Web applications is remarkably similar to working with databases in Windows applications. Most of what we've done in the previous three chapters still applies here, because the actual work you do with a database is still done in Visual Basic code (this time on the server).
The biggest differences come when you're working with binding data to controls, but even here, the process is similar to what you'd do in Windows forms. For example, as with Windows database programming, there are two types of data binding—simple and complex.