C#

<p>// This class can be instantiated by everyone.
public class MyClass
{
  public MyClass() { }
}</p>

<p>// Only classes in the same project can instantiate this class.
public class MyClass
{
  internal MyClass() { }
}</p>

<p>// This class can only be instantiated by itself.
public class MyClass
{
  private MyClass() { }

  public static MyClass CreateInstance()
  {
    return new MyClass();
  }
}</p>

DateTime dt;
if (!odr.IsDBNull(0))
  dt = odr.GetDateTime(0);

0xC00D1196: Incorrect user name or password<br />
The user name or password may be incorrect. <br />
To access a file that is located on a secure network, you must supply a user name and password for the network domain. <br />
Ensure that the user name and password that you are using are spelled correctly and are recognized by the network domain. <br />
It is not sufficient to use a user name and password for a local system account, which provides access to your computer but not the network.<br />
<br />
Error ID = 0xC00D1196, Condition ID = 0x00000000

<configuration>
  <appSettings>
    <add key="ConnectionString" value="your connection string"/>
  </appSettings>
</configuration>

string connString = ConfigurationSettings.AppSettings["ConnectionString"];
if (connString != null)
{
  OleDbConnection conn = new OleDbConnection(connString);
  //...
}

public DataSet dataset;
		private void Page_Load(object sender, System.EventArgs e)
		{
			
			string datapath = Server.MapPath("bin/csharp.mdb");
			string connString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"]+datapath;
			if (connString != null)
			{
				oleDbConnection1 = new System.Data.OleDb.OleDbConnection(connString);
				
			}
			oleDbConnection1.Open();
			OleDbDataAdapter dataadapter = new System.Data.OleDb.OleDbDataAdapter("select * from Csharp",oleDbConnection1);
			//dataset = new DataSet();
            //dataadapter.Fill(dataset,"Csharp");
			dataadapter.Fill(dataSet11,"Csharp");
			oleDbConnection1.Close();
			DropDownList1.DataTextField ="Help";
			DropDownList1.DataValueField="Help";
			DropDownList1.DataSource = dataSet11;
			DropDownList1.DataBind();
			
			
		}
		
		private void Button1_Click(object sender, System.EventArgs e)
		{
			TextBox2.Text = dataSet11.Csharp[DropDownList1.SelectedIndex].Information.ToString();
			
		}