tailieunhanh - Populating a Windows Forms ComboBox

[ Team LiB ] Recipe Populating a Windows Forms ComboBox Problem You need to populate a ComboBox from a database, bind a field in a database to the ComboBox so that the correct value is selected from the list, and use the value selected in the ComboBox to update the database. | Team LiB Recipe Populating a Windows Forms ComboBox Problem You need to populate a ComboBox from a database bind a field in a database to the ComboBox so that the correct value is selected from the list and use the value selected in the ComboBox to update the database. Solution You must Fill a ComboBox from a database pay attention to the difference between the SelectedIndex and SelectedValue . Bind a ComboBox to a field in a result set so that the value is selected in the ComboBox corresponding to the value in a field for the record displayed. Use the selection events returned by the ComboBox. Update the database with the value selected in the ComboBox. The schema of table TBL0711 used in this solution is shown in Table 7-11. Table 7-11. TBL0711 schema Column name Data type Length Allow nulls Id int 4 No ComboBoxItemId int 4 No Fieldl nvarchar 50 Yes The schema of table TBL0711_ComboBoxSource used in this solution is shown in Table 7-12. Table 7-12. TBL0711_ComboBoxSource schema Column name Data type Length Allow nulls ComboBoxItemId int 4 No Description nvarchar 50 No The sample code contains seven event handlers Sets up the sample by creating a DataAdapter with the logic to select all records from table TBL0709 in the sample database and to update changes made back to the database. The DataAdapter is used to fill a DataTable in a new DataSet with the schema and data from TBL0709. A DataTable is filled from table TBL0709_ComboBoxSource and added to the DataSet. A DataRelation is created between the two tables in the DataSet. The ComboBox control is filled by linking its properties to table TBL0709_ComboBoxSource in the DataSet. The text boxes displaying the data for the ID and Field1 columns and the ComboBox displaying data for the ComboBoxItemId column are bound to the DataTable TBL0709. Finally the BindingManagerBase is obtained for the TBL0709 table in the DataSet. Update Ends the current edit and uses the DataAdapter created in .