vb.net - Vb.net 将整数 DBNULL 转换为 0 - 错误

Question

我有这个方法：

Private Function convertInteger(intInteger As Object) As Integer

    If IsDBNull(intInteger) Then
        convertInteger = 0
    Else
        convertInteger = cInt(intInteger)
    End If

End Function

但它返回此错误：

未为类型“整数”和类型“dbnull”定义运算符“=”

我试图将 DBnull 值转换为 0..

但问题是我试图转换的值并不总是 DBnull .. 那么我应该如何处理呢？

Answer 1

尝试这个

Private Function convertInteger(intInteger As Object) As Integer

    If intInteger = DBNull.Value Then
        Return 0
    End If

    Return intInteger

End Function

正如 [Tim Schmelter] 所建议的，查看可空类型

Answer 2

尝试这个

Private Function convertInteger(ByVal intInteger As Object) as Integer
   If IsDBNull(intInteger) Then
       Return 0
   Else
       Return CInt(intInteger)
   End if
End Function

Answer 3

Private Sub readValue()
    Dim cSql As String
    Dim oCnn as OleDbConnection
    Dim oCmd as OleDbCommand
    Dim oDataReader as OleDbDataReader
    Dim valor as Integer

    oCnn.open()

    cSql = "SELECT FIELD_NAME FROM TABLE"
    oCmd = New OleDbCommand(cSql, oCnn)
    oReader = oCmd.executeReader

    if oReader.HasRows then
       oReader.read()
       valor = IIf(IsDBNull(oDataReader("FIELD_NAME")), 0, oDataReader("FIELD_NAME"))
    End If
End Sub