Ming Man Chan's Blog

Many developers still using C++ for some reasons. One of my customers is using VC++ but with open source database and he is not that happy with the database so he wants to change to Oracle database. This is a simple sample that I build for him with 1 button and 1 listbox.

When I was doing few lines of code for this sample I realize 2 not quite happy scenario in VC++; 1. The Oracle DataAccess Class does not appear in blue for example, OracleConnection, as compare to C#. 2. The intellisense is not as strong when comparing to C# as well.

The following are the few lines of code that in the sample:

static String ^ORA_CONNECTION_STRING = "Data Source=orcldemo;Persist Security Info=True;User ID=HR;Password=hr;";

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {

       OracleConnection ^conn = gcnew OracleConnection(ORA_CONNECTION_STRING);

       conn->Open();

       OracleCommand ^cmd = gcnew OracleCommand();

       cmd->Connection = conn;

       cmd->CommandText = "select department_id, department_name, city"

                + " from departments d, locations l" + " where d.location_id =

                   l.location_id";

        OracleDataReader ^dr = cmd->ExecuteReader();

       while (dr->Read())

       {

         listBox1->Items->Add("The " + dr->GetString(1) +

                           " department is in " + dr->GetString(2));

       }

       conn->Close();      

     }

Download the sample file from http://skydrive.live.com. The sample file name is WinAppCpp.zip. My MSN ID is chanmmn@hotmail.com

I found the easiest way to write a table or even tables from database to XML file is in.NET languages. To do this in Java you might probably need to include not only one but few proprietary library or open source jar file.

To do this in C#, one of the .NET languages, there is no additional reference need to be added to the project. Only using System.Data is needed because of the Dataset.

The code segment that writes dataset to XML file as follow (the code segment is from MSDN library):

    static void WriteXmlToFile(DataSet thisDataSet)

    {

      if (thisDataSet == null) { return; }

      // Create a file name to write to.

      string filename = "XmlDoc.xml";

      // Create the FileStream to write with.

      System.IO.FileStream stream = new System.IO.FileStream

          (filename, System.IO.FileMode.Create);

      // Write to the file with the WriteXml method.

      thisDataSet.WriteXml(stream);

}

The complete code to extract the data from employee table of HR schema to XML from is in http://skydrive.live.com. The sample file name is ConsoleDatasettoXML .zip. My MSN ID is chanmmn@hotmail.com.

If you are a .NET fan out there then you will basically hearing from many people asking, I have ADO.NET 2.0 so why is there a LINQ? It was a myth to me too. After Microsoft launch Service Pack 1 for Visual Studio 2008 then I clear some of my cloud in my head.

I will only mention one of the unique features here, ADO.NET Entity Data Model from ADO.NET Entity Framework. I have not found a better way to bind the Entity Model to DataGridView web control.

In order to create ADO.NET Entity Data Model, right click either Windows Application Project or Web Application Project and choose Add New Item… . Select ADO.NET Entity Data Model from the Add New Item dialog. After that you will have a file with edmx extension.

I have created a complete Windows Application sample using Northwind database in MS SQL 2008 Express. The Entity named NorthwindEntities. The entire sample consisted of 2 controls, 1 DataGridView and another is Button. I only have few lines of code in Button click event as below.

 private void btnGetCustomers_Click(object sender, EventArgs e)

{

  NorthwindEntities nwe = new NorthwindEntities();

  var cus = from customer in nwe.Customers

            select customer;

  dataGridView1.DataSource = cus;

}

I guess no one will ever say this is difficult.

The complete code is in http://skydrive.live.com. The sample file name is WinAppEntities.rar. My MSN ID is chanmmn@hotmail.com.


Unfortunately, ADO.NET Entity Data Model is not working with Oracle Database yet.