StateChangeEventArgs Class

Definition

Namespace:

System.Data

Assembly:

System.Data.Common.dll

Source:

StateChangeEvent.cs

Provides data for the state change event of a .NET data provider.

public ref class StateChangeEventArgs sealed : EventArgs

public sealed class StateChangeEventArgs : EventArgs

type StateChangeEventArgs = class
    inherit EventArgs

Public NotInheritable Class StateChangeEventArgs
Inherits EventArgs

Inheritance

Object

EventArgs

StateChangeEventArgs

Examples

The following example shows how to use the StateChange event within the SqlConnection class.

// Handler for OnStateChange event.
protected static void OnStateChange(object sender,
    StateChangeEventArgs e)
{
    PrintEventArgs(e);
}

static void Main()
{
    FillDataSet();
}

static private void FillDataSet()
{
    string connectionString = GetConnectionString();
    string queryString =
        "SELECT ProductID, UnitPrice from dbo.Products;";

    // Create a DataAdapter.
    using (SqlDataAdapter dataAdapter =
               new SqlDataAdapter(queryString, connectionString))
    {

        // Add the handlers.
        dataAdapter.SelectCommand.Connection.StateChange
            += new StateChangeEventHandler(OnStateChange);

        // Create a DataSet.
        DataSet dataSet = new DataSet();

        // Fill the DataSet, which fires several StateChange events.
        dataAdapter.Fill(dataSet, 0, 5, "Table");
    }
}

protected static void PrintEventArgs(StateChangeEventArgs args)
{
    Console.WriteLine("StateChangeEventArgs");
    Console.WriteLine("  OriginalState= {0} CurrentState= {1}",
        args.OriginalState, args.CurrentState);
}

static private string GetConnectionString()
{
    // To avoid storing the connection string in your code,
    // you can retrieve it from a configuration file.
    return "Data Source=(local);Initial Catalog=Northwind;"
        + "Integrated Security=true";
}

' Handler for the OnStateChange event.
Private Sub OnStateChange(ByVal sender As Object, _
    ByVal e As StateChangeEventArgs)
    PrintEventArgs(e)
End Sub

Sub Main()
    FillDataSet()
End Sub

Private Sub FillDataSet()
    Dim connectionString As String = GetConnectionString()
    Dim queryString As String = _
        "SELECT ProductID, UnitPrice from dbo.Products;"

    ' Create a DataAdapter.
    Using dataAdapter As New SqlDataAdapter( _
        queryString, connectionString)

        ' Add the handlers.
        AddHandler dataAdapter.SelectCommand.Connection.StateChange, _
            AddressOf OnStateChange

        ' Create a DataSet.
        Dim dataSet As New DataSet()

        ' Fill the DataSet, which fires several StateChange events.
        dataAdapter.Fill(dataSet, 0, 5, "Table")
    End Using
End Sub

Private Sub PrintEventArgs(ByVal args As StateChangeEventArgs)
    Console.WriteLine("StateChangeEventArgs")
    Console.WriteLine("  OriginalState= {0} CurrentState= {1}", _
        args.OriginalState, args.CurrentState)
End Sub

Private Function GetConnectionString() As String
    ' To avoid storing the connection string in your code,  
    ' you can retrieve it from a configuration file.
    Return "Data Source=(local);Initial Catalog=Northwind;" _
       & "Integrated Security=true;"
End Function

Remarks

The data is used by the StateChange property of the OleDbConnection and the StateChange property of the SqlConnection.

Constructors

StateChangeEventArgs(ConnectionState, ConnectionState)

Initializes a new instance of the StateChangeEventArgs class, when given the original state and the current state of the object.

Properties

CurrentState	Gets the new state of the connection. The connection object will be in the new state already when the event is fired.
OriginalState	Gets the original state of the connection.

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)