7. Updating Example Dim adapter As New SqlDataAdapter() Dim delete As New SqlCommand("DeleteOrder", cnn) delete.CommandType = CommandType.StoredProcedure delete.Parameters.Add("@OrderID", SqlDbType.Int).SourceColumn = "OrderID" adapter.DeleteCommand = delete Dim insert As New SqlCommand("AddOrder", cnn) insert.CommandType = CommandType.StoredProcedure insert.Parameters.Add("@OrderID", SqlDbType.Int).SourceColumn = "OrderID" insert.Parameters.Add("@CustD", SqlDbType.Int).SourceColumn = "CustomerID" insert.Parameters.Add("@Date", SqlDbType.DateTime).Value = DateTime.Now adapter.InsertCommand = insert Dim update As New SqlCommand("UpdateOrder", cnn) update.CommandType = CommandType.StoredProcedure update.Parameters.Add("@OrderID",SqlDbType.Int).SourceColumn="OrderID" update.Parameters.Add("@CustD",SqlDbType.Int).SourceColumn="CustomerID" adapter.UpdateCommand = update adapter.Update(ordersTable)
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10. Pessimistic Concurrency 'Start a transaction and set on Select command Dim connect = adapter.SelectCommand.Connection connect.Open() Dim tran = connect.BeginTransaction(IsolationLevel.Serializable) adapter.SelectCommand.Transaction = tran 'Fill DataSet and make changes adapter.Fill(ds, "Employees") Dim employee As DataRow For Each employee In ds.Tables("Employees").Rows employee("Salary") = employee("Salary") * 1.1 Next 'Set the connection and transaction for the update command adapter.UpdateCommand.Connection = connect adapter.UpdateCommand.Transaction = tran adapter.Update(ds,"Employees") tran.Commit() connect.Close()
11. Scrollable Server Cursors ' Declare and open cursor Dim cmd As New SqlCommand(Nothing, conn) cmd.CommandText = “DECLARE mycursor SCROLLABLE CURSOR FOR select * from Customers” cmd.ExecuteNonQuery() cmd.CommandText = “OPEN mycursor” cmd.ExecuteNonQuery() ' Read from cursor Dim dr As SqlDataReader cmd.CommandText = “FETCH NEXT FROM mycursor” While(True) dr =cmd.ExecuteReader() if (dr.Read() = false) Then Exit While Console.WriteLine("CompanyName is " & dr("CompanyName")) dr.Close() End While ' Update fifth row cmd.CommandText = “FETCH ABSOLUTE 5 FROM mycursor” cmd.ExecuteNonQuery() cmd.CommandText = “UPDATE Customers set FirstName = ‘Bill’ WHERE CURRENT OF mycursor” cmd.ExecuteNonQuery() ' Close the cursor cmd.CommandText = “CLOSE mycursor; DEALLOCATE mycursor” cmd.ExecuteNonQuery()
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16. Inserting AutoIncrement Values Sub UpdateData(table As DataTable) ' Set InsertCommand with returned Identity Dim insert As New SqlCommand( _ "Insert into Orders(OrderID,Date) values @OrderID, @Date)" _ & ";Select SCOPE_IDENTITY() as OrderID ",cnn) insert.Parameters.Add("@OrderID",SqlDbType.Int).SourceColumn="OrderID" insert.Parameters.Add("@Date",SqlDbType.DateTime).Value = DateTime.Now adapter.InsertCommand = insert ' Set UpdateRowSource and Register RowUpdatedEventHandler insert.UpdatedRowSource = UpdateRowSource.FirstReturnedRecord AddHandler adapter.RowUpdated, _ New SqlRowUpdatedEventHandler(AddressOf myHandler) DataAdapter.Update(table) End Sub Shared Sub myHandler(adapter as Object, e As SqlRowUpdatedEventArgs) ' Don't call AcceptChanges e.Status = UpdateStatus.SkipCurrentRow End Sub
