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Kết quả lấy từ SQL Server bằng cách sử dụng các đối tượng DataTable Người đọc dữ liệu là rất tốt khi bạn chỉ muốn tải dữ liệu vào một ListBox ComboBox hoặc kiểm soát bằng tay, nhưng bạn có thể tiết kiệm một số mã hóa bằng cách ràng buộc các điều khiển ListBox để một bảng dữ liệu ở thời gian chạy | 3.2 Retrieve Results from SQL Server by Using the DataTable Object The data reader is great when you just want to load data into a ListBox or ComboBox control manually but you can save some coding by binding the ListBox control to a data table at runtime as well as providing the ability to get not only the displayed value but the key column as well. This How-To demonstrates how to bind a limited ListBox control to a data table. Although getting the quick information is great you need to be able to refer back to the table of information and you don t want to have to open another connection to get there. You know that the DataTable object should allow you to perform this task. How do you get results from SQL Server by using the DataTable object Technique Using the Windows Forms controls that were introduced in How-To 3.1 you will use a familiar object from Chapter 1 called the DataAdapter object. This time instead of using the OleDbDataAdapter data control you will use the OleDbDataAdapter class from the System.Data.OleDb Namespace. Using a similar technique that was used when filling a DataSet you will instantiate the data adapter by assigning the SQL string and connection object. Then instead of filling a DataSet object you will fill a DataTable object. Because you will only be dealing with a table s worth of data you just need to use a data table. That way you will be able to perform lookups more conveniently as shown in the next How-To. For now the next step will be to assign the following properties of the list box DataSource. This will be set to the DataTable object-in this case dtCust. DisplayMember. This specifies which column from the data table to use for display in the list box. ValueMember. Here you will specify which column you want to use for the value that is retrieved when an item is selected from the list box. By programming the ListBox control using this technique you can access the ValueMember column in the Selectitem property of the list box. .
