vb.net - INSERT... ON DUPLICATE KEY UPDATE.... 这是错误 .System.NullReferenceException:Object reference not set to an instance of an object

Question

再会，

我有这个错误 System.NullReferenceException:Object reference not set to an instance of an object。当我触发更新按钮时。我的表单 1 中有一个列表视图，因此我可以添加工作正常的数据并接受空白值，以便用户将来可以添加数据。但是当我尝试插入...更新时复制密钥时，我遇到了这个错误。

 Dim cmd6 As New MySqlCommand(cs, conn2)
                With cmd6
                    .CommandText = "INSERT INTO workrecord (entryno, empid2, position, company, sdate, edate, yoservice, reason)" _
                     & "VALUES (@entryno, @empid2, @position, @company, @sdate, @edate, @yoservice, @reason)" _
                     & "ON DUPLICATE KEY UPDATE entryno = @entryno, empid2 = @empid2, position = @position, company = @company, sdate = @sdate, edate = @edate, yoservice = @yoservice, reason = @reason"
                    .Parameters.AddWithValue("@entryno", itm1.Text)
                    .Parameters.AddWithValue("@empid2", itm1.SubItems(1).Text)
                    .Parameters.AddWithValue("@position", itm1.SubItems(2).Text)
                    .Parameters.AddWithValue("@company", itm1.SubItems(3).Text)
                    .Parameters.AddWithValue("@sdate", itm1.SubItems(4).Text)
                    .Parameters.AddWithValue("@edate", itm1.SubItems(5).Text)
                    .Parameters.AddWithValue("@yoservice", itm1.SubItems(6).Text)
                    .Parameters.AddWithValue("@reason", itm1.SubItems(7).Text)
                    .ExecuteNonQuery()
                End With

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