如何使用linq从数据库中删除记录？

Question

我试图用LINQ从数据库中删除一条记录。我给系统的行键删除，它确实返回一行。

这里是我的代码：

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