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Devart.Data.SqlServer Namespace / SqlDataReader Class / IsDBNull Method / IsDBNull(Int32) Method
Example

In This Topic
    IsDBNull(Int32) Method
    In This Topic
    Gets a value indicating whether the column contains non-existent or missing values.
    Syntax
    'Declaration
     
    Public Overloads Overrides Function IsDBNull( _
       ByVal i As Integer _
    ) As Boolean
    public override bool IsDBNull( 
       int i
    )

    Parameters

    i

    Return Value

    true if the specified column value is equivalent to System.DBNull; otherwise, false.
    Remarks
    To avoid raising an error, call this method to check for null column values before calling the typed Get methods (for example, GetByte, GetChar, and so on).
    Example
    static void GetMyValue(SqlConnection myConnection)
    {
      SqlCommand cmd = new SqlCommand("SELECT * FROM Test.AllTypes");
      cmd.Connection = myConnection;
      myConnection.Open();
      try
      {
        SqlDataReader reader = cmd.ExecuteReader();
        reader.Read();
    
        for (short i = 0; i < reader.FieldCount; i++)
        {
          if (reader.IsDBNull(i))
            Console.WriteLine("NULL");
          else
          {
            object someValue = reader.GetValue(i);
            Console.WriteLine(someValue.ToString());
          }
        }
    
        reader.Close();
      }
      finally
      {
        myConnection.Close();
      }
    }
    Shared Sub GetMyValue(ByVal myConnection As SqlConnection)
      Dim cmd As New SqlCommand("SELECT * FROM Test.AllTypes")
      cmd.Connection = myConnection
      myConnection.Open()
      Try
        Dim reader As SqlDataReader = cmd.ExecuteReader
        reader.Read()
        For i As Short = 0 To reader.FieldCount - 1
          If reader.IsDBNull(i) Then
            Console.WriteLine("NULL")
          Else
            Console.WriteLine(reader.GetValue(i).ToString)
          End If
        Next i
        reader.Close()
      Finally
        myConnection.Close()
      End Try
    End Sub
    Requirements

    Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

    See Also