gender.vb

SQL2005开发指南

Imports System
Imports System.Data
Imports System.Data.Sql
Imports System.Data.SqlTypes
Imports Microsoft.SqlServer.Server
Imports System.IO

<Serializable()> _
<Microsoft.SqlServer.Server.SqlUserDefinedType _
 (Format.UserDefined, _
  IsFixedLength:=True, MaxByteSize:=2)> _
Public Structure Gender
    Implements INullable, IBinarySerialize

    Public Overrides Function ToString() As String
        If m_value.IsNull = False Then
            Return m_value.Value
        Else
            Return Nothing
        End If
    End Function
    Public Sub Read(ByVal r As BinaryReader) _
        Implements IBinarySerialize.Read
        m_value = r.ReadString.ToString()
    End Sub
    Public Sub Write(ByVal w As BinaryWriter) _
        Implements IBinarySerialize.Write
        w.Write(m_value.ToString())
    End Sub

    Public ReadOnly Property IsNull() As Boolean _
      Implements INullable.IsNull
        Get
            If m_value.IsNull = True Then
                Return True
            Else
                Return False
            End If
        End Get
    End Property

    Public Shared ReadOnly Property Null() As Gender
        Get
            Dim h As Gender = New Gender
            h.m_Null = True
            Return h
        End Get
    End Property

    Public Shared Function Parse(ByVal s As SqlString) As Gender
        If s.IsNull Then
            Return Null
        End If

        Dim u As Gender = New Gender
        u.Value = s
        Return u
    End Function

    ' Create a Value Property
    Public Property Value() As SqlString
        Get
            Return m_value
        End Get

        Set(ByVal value As SqlString)
            If (value = "M" Or value = "F") Then
                m_value = value
            Else
                Throw New ArgumentException _
                  ("Gender data type must be M or F")
            End If
        End Set
    End Property

    ' Private members
    Private m_Null As Boolean
    Private m_value As SqlString

End Structure