当错误再次出现时错误处理不起作用

问题描述

逻辑:

• 用户.按下按钮；
• 代码.创建一个记录集"rstStud"(学生)和rstGroupStud"(学生组)；
• 代码.循环.枚举rstStud"；
  • 代码.添加条目到rstGroupStud"；
  • 代码.如果该记录存​​在，则转到循环中的下一条记录；
  • 代码.如果条目是新条目，则在rstGroupStud"中添加条目；
    本质:一键点击 - 添加一个独特的条目.

  问题.
  当循环过去！StudentName = "Student Name 2" 在.Update"行中出现错误.
  错误:
  "由于重复值导致更改失败索引、主键或关系.一改数据或包含重复值的多个字段删除索引或通过允许覆盖它重复值并重试.

  换句话说，错误处理程序第一次正常工作，当我重新触发时，我得到一个错误.

  In other words, the first time the error handler works normally, and when I re-fire, I get an error.

  问题.
  如何让代码按照描述的逻辑运行?

  Question.
  How to make the code work according to the described logic?

  Private Sub btnAddRecord_Click()
      Dim nameStud As String
  
      Dim rstStud As DAO.Recordset   '
      Dim rstGroupStud As DAO.Recordset '
  
      Set rstStud = CurrentDb.OpenRecordset("tbl_02_Students", dbOpenSnapshot)  '
      Set rstGroupStud = CurrentDb.OpenRecordset("tbl_03_GruopsStudents", dbOpenDynaset)  '
  
      ' *** rstStud
      With rstStud
          Do Until .EOF = True
              nameStud = !nameStud
  
              On Error GoTo errend
              ' *** rstGroupStud
              With rstGroupStud
                  .AddNew
  
                  !idGroup = Me.id_GroupFrm
                  !nameStud = nameStud
                  ' nameStud
                  .Update
              End With
              rstGroupStud.Close
              Me.frm_03_GruopsStudents_tbl.Requery
  
              Exit Sub
  errend:
              .MoveNext
          Loop
      End With
  
      On Error Resume Next
      rstStud.Close
      Set rstStud = Nothing
  End Sub
  

  更新_1
  文件 - 链接

  推荐答案

  你需要解开执行路径；正常和错误执行状态是交织在一起的，这就是为什么不能处理超出第一个错误的任何错误.

  You need to de-tangle the execution paths; normal and error execution states are intertwined, that's why any error beyond the first one can't be handled.

  Private Sub btnAddRecord_Click()
      Dim nameStud As String
  
      Dim rstStud As DAO.Recordset   '
      Dim rstGroupStud As DAO.Recordset '
  
      Set rstStud = CurrentDb.OpenRecordset("tbl_02_Students", dbOpenSnapshot)  '
      Set rstGroupStud = CurrentDb.OpenRecordset("tbl_03_GruopsStudents", dbOpenDynaset)  '
  
      ' *** rstStud
      With rstStud
          Do Until .EOF = True
              On Error GoTo ErrHandler
              nameStud = !nameStud
  
              ' *** rstGroupStud
              With rstGroupStud
                  .AddNew
  
                  !idGroup = Me.id_GroupFrm
                  !nameStud = nameStud
                  ' nameStud
                  .Update
              End With
              rstGroupStud.Close
              Me.frm_03_GruopsStudents_tbl.Requery
  
              Exit Do
  TryNext:
              On Error Resume Next
              .MoveNext
              If Err.Number <> 0 Then Exit Do
              On Error GoTo 0
          Loop
      End With
  
      On Error Resume Next
      rstStud.Close
      Set rstStud = Nothing
      On Error GoTo 0
      Exit Sub
  
  ErrHandler:
      Resume TryNext
  End Sub
  

  那样 ErrHandler 只会在错误状态下运行；TryNext 在happy path"中运行，Exit Do 跳出循环(但不跳出程序)，这样无论结果如何，清理代码都可以运行.

  That way ErrHandler only ever runs in an error state; TryNext runs in the "happy path", and Exit Do breaks out of the loop (but not out of the procedure) so that the cleanup code can run whatever the outcome is.

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