將SQL NULL綁定到ASP.NET控件的正確方法？

Question

我有我已經綁定到一個SQL結果ASP.NET控件：

<asp:GridView ID="EmployeeSearchResults" runat="server" AutoGenerateColumns="False" > 
    <Columns> 
    <asp:TemplateField HeaderText="Status" SortExpression="Status"> 
     <ItemTemplate> 
     <asp:Label ID="Label1" runat="server" Text='<%# (EmployeeSearchStatus(Eval("SeparationDate"),Eval("PositionTitle"),Eval("EffectiveDate"))) %>'></asp:Label> 
     </ItemTemplate> 
    </asp:TemplateField>             
    </Columns> 
</asp:GridView> 

我EmployeeSearchStatus功能非常基本的，用於測試傳遞NULL中的值，並創建一個字符串顯示：

Public Function EmployeeSearchStatus(ByVal SeparationDate As Object, ByVal PositionTitle As Object, ByVal EffectiveDate As Object) As String 
    Dim ReturnString As String = "" 
    If IsDBNull(SeparationDate) Then 
     ReturnString = "Currently Employed as " 
    Else 
     ReturnString = "Last Employed as " 
    End If 
    ReturnString += PositionTitle 
    If IsDBNull(SeparationDate) Then 
     ReturnString += " (effective " + EffectiveDate + ")." 
    Else 
     ReturnString += " (separated on " + SeparationDate + ")." 
    End If 
    Return ReturnString 
End Function 

這是處理從SQL返回到ASP.NET控件的NULL值的正確方法嗎？有更好的技術嗎？

感謝，

羅素

Answer 1

您的代碼看起來不錯，雖然你可能把它簡化一點，如果你想：

Public Function EmployeeSearchStatus(ByVal SeparationDate As Object, ByVal PositionTitle As Object, ByVal EffectiveDate As Object) As String 
    If IsDBNull(SeparationDate) Then 
     Return "Currently Employed as " + PositionTitle + " (effective " + EffectiveDate + ")." 
    Else 
     Return "Last Employed as " + PositionTitle + " (separated on " + SeparationDate + ")." 
    End If 
End Function 

的代碼不承擔，但是，PositionTitle和EffectiveDate永遠不會是null。如果這不是在數據庫中強制執行的，則可以在代碼中添加一些檢查來處理這些情況。