如何用VB.NET判断数据库的BIT值的0和空？

'还是拿你的数据做例子
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim connStr As String = "SERVER=.;UID=sa;PWD=;DATABASE=ceshi"
        Dim conn As SqlClient.SqlConnection = New SqlClient.SqlConnection(connStr)
        Dim rs As New SqlClient.SqlDataAdapter
        Dim mydata As New DataSet()
        Dim cmd As SqlCommand = conn.CreateCommand
        Dim sql As String = "select * from [admin]  where [kd_xsdh]='user'"
         = sql
        conn.Open()
        rs.SelectCommand = cmd
        rs.Fill(mydata, "1")
        Try
            Select Case mydata.Tables(0).Rows(0)("kd_zuofei").ToString
                Case "True"
                    MsgBox("bit值为 1")
                Case "False"
                    MsgBox("bit值为 0")
                Case Else
                    MsgBox(" bit值为空值")
            End Select
            conn.Close()
        Catch ex As Exception
            MsgBox("数据库中没有此记录")
        End Try

    End Sub