SqlDataAdapter custDA = new SqlDataAdapter("SELECT CustomerID, CompanyName FROM Customers ORDER BY CustomerID", nwindConn);
//1. Should i put this update operations within the same method block with the select operations? //The Update command checks for optimistic concurrency violations in the WHERE clause. custDA.UpdateCommand = new SqlCommand("UPDATE Customers (CustomerID, CompanyName) VALUES(@CustomerID, @CompanyName) " + "WHERE CustomerID = @oldCustomerID AND CompanyName = @oldCompanyName", nwindConn); custDA.UpdateCommand.Parameters.Add("@CustomerID", SqlDbType.NChar, 5, "CustomerID"); custDA.UpdateCommand.Parameters.Add("@CompanyName", SqlDbType.NVarChar, 30, "CompanyName"); //Pass the original values to the WHERE clause parameters. SqlParameter myParm;
//2. Why should i include a SQLParameter assignment here? myParm = custDA.UpdateCommand.Parameters.Add("@oldCustomerID", SqlDbType.NChar, 5, "CustomerID");
//3. What his "myParm.SourceVersion" does? Does it sore the Original fetched value in the select
//statement?
myParm.SourceVersion = DataRowVersion.Original;
myParm = custDA.UpdateCommand.Parameters.Add("@oldCompanyName", SqlDbType.NVarChar, 30, "CompanyName"); myParm.SourceVersion = DataRowVersion.Original;
//Add the RowUpdated event handler. custDA.RowUpdated += new SqlRowUpdatedEventHandler(OnRowUpdated); DataSet custDS = new DataSet();
//the value custDA.Fill(custDS, "Customers"); //4. why did the author call the update() in here? Why he put Fill() and UPdate() in the same
//method block? custDA.Update(custDS, "Customers");