IsDBNull(Int32) Method

In This Topic

Gets a value indicating whether the column contains non-existent or missing values.

Syntax

Visual Basic
C#

'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

csharp

static void GetMyValue(MySqlConnection myConnection)
{
  MySqlCommand cmd = new MySqlCommand("SELECT * FROM Test.AllTypes");
  cmd.Connection = myConnection;
  myConnection.Open();
  try
  {
    MySqlDataReader 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();
  }
}

Visual Basic

Shared Sub GetMyValue(ByVal myConnection As MySqlConnection)
  Dim cmd As New MySqlCommand("SELECT * FROM Test.AllTypes")
  cmd.Connection = myConnection
  myConnection.Open()
  Try
    Dim reader As MySqlDataReader = 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

Reference

MySqlDataReader Class
MySqlDataReader Members
Overload List

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