You use Visual Studio .NET to develop a Windows based application that interacts with a Microsoft SQL Server database. The form CustomerForm contains a SqlConnection named XYZConnection, a SqlDataAdapter named XYZDataAdapter, a DataSet named XYZDataSet, and several TextBox controls bound to columns in XYZDataSet. The application connects successfully, but no data appears in the text boxes. During the CustomerForm.Load event, which action must occur so that the bound text boxes display data from the database?

Introduction / Context:
In a Windows Forms application that uses ADO.NET, data binding between controls and a DataSet object is very common. However, binding the controls at design time is not enough. The DataSet must actually be filled with data at runtime. This question checks whether you understand which ADO.NET method is responsible for moving data from the database into the DataSet so that bound controls such as TextBox controls show values.

Given Data / Assumptions:

• There is a SqlConnection named XYZConnection.
• There is a SqlDataAdapter named XYZDataAdapter configured with a valid SELECT command.
• There is a DataSet named XYZDataSet with a DataTable that matches the result set.
• TextBox controls are bound to columns in XYZDataSet using the DataBindings property.
• The application connects to the database without connection errors, but the text boxes remain empty.

Concept / Approach:
Data binding in Windows Forms works by connecting control properties to data sources such as DataTables or DataSets. But the DataSet is initially empty. You must call the Fill method of the DataAdapter at runtime to execute the SELECT query and populate the DataSet with rows. Once the DataSet has data, the binding infrastructure can pull values from the current row into the TextBox controls. Other methods, such as FillSchema or BeginInit, do not actually populate the DataSet with row data.

Step-by-Step Solution:
Step 1: Identify the purpose of the SqlDataAdapter. It acts as a bridge between the database and the DataSet.Step 2: Recall that SqlDataAdapter.Fill(DataSet) executes the associated SELECT command and loads the result set into tables inside the DataSet.Step 3: Note that the DataBindings on the TextBox controls expect that XYZDataSet already contains rows before the form is displayed.Step 4: During the CustomerForm.Load event, you should call XYZDataAdapter.Fill(XYZDataSet).Step 5: After Fill completes, the current record in the bound DataTable will supply values that are automatically shown in the text boxes.
Verification / Alternative check:
A quick test is to place a breakpoint in the Load event, call XYZDataAdapter.Fill(XYZDataSet), and then inspect XYZDataSet.Tables[0].Rows.Count in the debugger. If the count is greater than zero, you have populated the DataSet correctly. When execution continues, the form should show the first row values in the bound TextBox controls. If Fill is not called, the row count stays at zero and the controls remain blank.

Why Other Options Are Wrong:
Option A, calling BeginInit on XYZDataSet, is related to component initialization, not data loading. Option B, explicitly opening XYZConnection, is not required because Fill opens and closes the connection automatically if needed. Option C, FillSchema, only retrieves schema information such as column definitions, not actual data rows. Therefore, only option D, calling Fill and passing XYZDataSet, completes the data population step required for binding to work.

Common Pitfalls:
Developers sometimes think that setting up data binding at design time and configuring the DataAdapter is enough, forgetting that the DataSet starts empty. Another common mistake is confusing FillSchema with Fill or trying to manually set control values instead of letting binding do the work. Remember that Fill is the key step that moves data from the database into the in memory DataSet, enabling your controls to display dynamic content.

Final Answer:
The correct action is to execute the Fill method of XYZDataAdapter and pass XYZDataSet in the form load event.