What does the following code do?



1 int m_intAge;

2 objSelectAgeData.Parameters[ "Name" ].Value = "Bob";

3

4 objOleDbConnection.Open();

5

6 OleDbDataReader objReader =

7 objSelectAgeData.ExecuteReader();

8

9 objReader.Read();

10

11 m_intAge = Convert.ToInt32( objReader[ "Age" ] );

12

13 objReader.Close();

14 objOleDbConnection.Close();

This code segment connects to a database and retrieves the Age data for the person with the name Bob. This data is then stored in m_intAge. The code then closes both the data reader and the connection to the database. For this example, a sample database named Employees.mdb has been provided in the bin\debug directory. Follow the instructions previously presented in this tutorial to establish a connection to the database. The complete code reads:




 // GetAge.cs





 using System;


 using System.Drawing;


 using System.Collections;


 using System.ComponentModel;


 using System.Windows.Forms;


 using System.Data;


 using System.Data.OleDb;





 namespace GetAge


 {


 /// 


 /// Summary description for FrmGetAge.


 /// 



 public class FrmGetAge : System.Windows.Forms.Form


 {


 private System.Windows.Forms.Label lblAgeOut;


 private System.Windows.Forms.Label lblAge;


 private System.Windows.Forms.Label lblNameOut;


 private System.Windows.Forms.Label lblName;


 private System.Data.OleDb.OleDbConnection objOleDbConnection;


 private System.Data.OleDb.OleDbCommand objSelectAgeData;


 /// 


 /// Required designer variable.


 /// 



 private System.ComponentModel.Container components = null;





 public FrmGetAge()


 {


 //


 // Required for Windows Form Designer support


 //


 InitializeComponent();





 //


 // TODO: Add any constructor code after InitializeComponent


 // call


 //


 }





 /// 


 /// Clean up any resources being used.


 /// 



 protected override void Dispose( bool disposing )


 {


 if( disposing )


 {


 if (components != null)


 {


 components.Dispose();


 }


 }


 base.Dispose( disposing );


 }





 // Windows Form Designer generated code





 /// 


 /// The main entry point for the application.


 /// 



 [STAThread]


 static void Main()


 {


 Application.Run(new FrmGetAge());


 }





 // retrieves and displays the age of Bob from "Employees.mdb"


 // in the "bin\debug" directory


 private void FrmGetAge_Load(


 object sender, System.EventArgs e )


 {


int m_intAge;


objSelectAgeData.Parameters[ "Name" ].Value = "Bob";


objOleDbConnection.Open();


OleDbDataReader objReader =


objSelectAgeData.ExecuteReader();


objReader.Read();


m_intAge = Convert.ToInt32( objReader[ "Age" ] );


objReader.Close();


objOleDbConnection.Close();





 lblAgeOut.Text = Convert.ToString( m_intAge );





 } // end method FrmGetAge_Load


 } // end class FrmGetAge


 }