如何使用linq從數據庫中刪除記錄？

Question

我試圖用LINQ從數據庫中刪除一條記錄。我給系統的行鍵刪除，它確實返回一行。

這裏是我的代碼：

Public Function DeleteHydrantByKey(ByVal objDeptGUID As String, ByVal objLogonToken As String, ByVal objSesionToken As String, ByVal objHydrantKey As Integer) As String 
    'Check if Token is good 
    If CheckToken(objSesionToken, objDeptGUID) = False Then 
     Return "Session Error" 
    End If 
    'Check if login Token is good 
    If CheckLoginToken(objDeptGUID, objLogonToken) = False Then 
     Return "Logon Session Error" 
    End If 

    Try 
     Dim lbHydrants As New linqAlarmDumpDataContext 

     'Check for Hydrans in system 
     Dim GetHydrants = From r In lbHydrants.tbHydrants _ 
          Where r.key = objHydrantKey 
          Select r 

     'Check For Hydrent Data 
     If GetHydrants.Count = 0 Then 
      Return "Not Found" 
     End If 


     'Deletes Hydrent Data After Check was ok 
     lbHydrants.tbHydrants.DeleteOnSubmit(GetHydrants) 
     lbHydrants.SubmitChanges() 



     Return "OK" 
    Catch ex As Exception 
     Return "Error" 
    End Try 
End Function 

Answer 1

Public Function DeleteHydrantByKey(ByVal objDeptGUID As String, ByVal objLogonToken As String, ByVal objSesionToken As String, ByVal objHydrantKey As Integer) As String 
    'Check if Token is good 
    If CheckToken(objSesionToken, objDeptGUID) = False Then 
     Return "Session Error" 
    End If 
    'Check if login Token is good 
    If CheckLoginToken(objDeptGUID, objLogonToken) = False Then 
     Return "Logon Session Error" 
    End If 

    Try 
     Dim lqHydrants As New linqAlarmDumpDataContext 

     'Check for Hydrans in system 
     Dim GetHydrants = From r In lqHydrants.tbHydrants _ 
          Where r.key = objHydrantKey 
          Select r 

     'Check For Hydrent Data 
     If GetHydrants.Count = 0 Then 
      Return "Not Found" 
     End If 


     'Deletes Hydrent Data After Check was ok 
     lqHydrants.tbHydrants.DeleteAllOnSubmit(GetHydrants) 
     lqHydrants.SubmitChanges() 



     Return "OK" 
    Catch ex As Exception 
     Return "Error" 
    End Try 
End Function