Question

我的代码正在尝试

首先：查找值是否在第0列＆＃34; CODE＆＃34;
第二：如果找到，请检查第1列和第34列;状态＆＃34;具有＆＃34; IN＆＃34;的价值如果为真，则MsgBox显示消息＆＃34;使用票证＆＃34; 如果值为空，则将值更改为IN

这是我的代码：

    Private Sub changefound()

    Dim findtxt As String = txt_Find.Text
    Try
        If DataGridView2.Rows.Count > 0 Then
            For i As Integer = 0 To DataGridView2.Rows.Count - 1
                ' For j As Integer = 0 To DataGridView2.Columns.Count - 1 'Not using this because we only want to look in CODE column.
                Dim CellChange As String = DataGridView2.Rows(i).Cells("CODE").Value.ToString

                If CellChange.Contains(findtxt) = True Then
                    If DataGridView2.Rows(i).Cells("STATUS").Value = "IN" Then    'This is Line 366
                        MsgBox("Tickets USed")
                        Exit Sub


                    Else
                        With DataGridView2
                            ' .Rows(i).Cells(j).Style.BackColor = Color.Gray
                            '  .Rows(i).Cells(j).Value = findtxt
                            ' MsgBox(i & j + 1)

                            .Rows(i).Cells("STATUS").Value = "IN"


                            Exit Sub
                        End With
                    End If
                End If
                    'Next   'This is the Jfor 
            Next
        End If
    Catch e As Exception
        MessageBox.Show(e.ToString())
    End Try


End Sub

任何方式我移动它只会检查是否找到了它将MSGBox使用的票。如果单元格没有值，则会锁定错误：

System.InvalidCastException：操作＆＃39; =＆＃39;未定义类型＆＃34; DBNull＆＃34;   和字符串＆＃34; IN＆＃34;
  在   main.vb：line366

任何帮助？

Answer 1

在进行比较之前添加DbNull检查：

.....
If Not IsDbNull(DataGridView2.Rows(i).Cells("STATUS").Value) _
        AndAlso DataGridView2.Rows(i).Cells("STATUS").Value = "IN" Then 
.....

阅读以下主题以获取处理DbNull数据的更多选项： handling dbnull data in vb.net

如何检查Cell In Datagridview中是否有值并继续VB.Net

1 个答案: