// Namespaces, Variables, and Constants using System; using System.Configuration; using System.Data; private OleDbDataAdapter da; private DataTable dt; private void Excel_Load(object sender, System.EventArgs e) {     // Create the DataAdapter.     da = new OleDbDataAdapter("SELECT * FROM [Sheet1$]", ConfigurationSettings.AppSettings["ExcelConnectString1"]);     // Create the insert command.     String insertSql = "INSERT INTO [Sheet1$] (CategoryID, CategoryName, Description) VALUES (?, ?, ?)";     da.InsertCommand = new OleDbCommand(insertSql, da.SelectCommand.Connection);     da.InsertCommand.Parameters.Add("@CategoryID", OleDbType.Integer, 0, "CategoryID");     da.InsertCommand.Parameters.Add("@CategoryName", OleDbType.Char, 15, "CategoryName");     da.InsertCommand.Parameters.Add("@Description", OleDbType.VarChar, 100, "Description");     // Create the update command.     String updateSql = "UPDATE [Sheet1$] SET CategoryName=?, Description=? " WHERE CategoryID=?";     da.UpdateCommand = new OleDbCommand(updateSql, da.SelectCommand.Connection);     da.UpdateCommand.Parameters.Add("@CategoryName", OleDbType.Char, 15, "CategoryName");     da.UpdateCommand.Parameters.Add("@Description", OleDbType.VarChar, 100, "Description");     da.UpdateCommand.Parameters.Add("@CategoryID", OleDbType.Integer, 0, "CategoryID");     // Fill the table from the Excel spreadsheet.     dt = new DataTable( );     da.Fill(dt);     // Define the primary key.     dt.PrimaryKey = new DataColumn[] {dt.Columns[0]};     // Records can only be inserted using this technique.     dt.DefaultView.AllowDelete = false;     dt.DefaultView.AllowEdit = true;     dt.DefaultView.AllowNew = true;     // Bind the default view of the table to the grid.     dataGrid.DataSource = dt.DefaultView; } private void updateButton_Click(object sender, System.EventArgs e) {     da.Update(dt); }