Question

我正在使用vb.net windows窗体，我有一个数据网格视图，我正在尝试保存数据网格值

我将数据保存到两个表...我的表名：

1->CompanyMaster_tbl
2->DepartmentMaster_tbl

我在保存按钮中给出了代码：

Dim CompanyMaster_tbl As DataTable = Nothing
        Dim DepartmentMaster_tbl As DataTable = Nothing

        For Each CompanyMaster_row As DataRow In CompanyMaster_tbl.Rows
            For i As Integer = 0 To gv.RowCount - 2

                If gv.Rows(i).Cells("cmpny").Value <> "" Then
                    sqlInsertT1 &= "Insert Into CompanyMaster_tbl(CompanyName) Values ('" & gv.Rows(i).Cells("cmpny").Value & "');"
                    Exetransaction(sqlInsertT1)
                End If
                Ccid = RecordID("Cid", "CompanyMaster_tbl", "CompanyName", gv.Rows(i).Cells("cmpny").Value)
            Next

            For Each DepartmentMaster_row As DataRow In DepartmentMaster_tbl.Select(Ccid)
                For j As Integer = 0 To gv.RowCount - 2
                    sqlInsertT2 &= "Insert Into DepartmentMaster_tbl(dtname,dtphone,dtEmail,Cid) Values ('" & gv.Rows(j).Cells("Dpmnt").Value & "','" & gv.Rows(j).Cells("dtphon").Value & "','" & gv.Rows(j).Cells("mail").Value & "'," & Ccid & ");"
                    Exetransaction(sqlInsertT2)
                Next
            Next
        Next

来到这条线时出现错误：

For CompanyMaster_row As DataRow In CompanyMaster_tbl.Rows

对象引用未设置为对象的实例为什么我收到此错误？我的代码有什么问题

Answer 1

我不在VB.NET中工作（而是在C＃中工作），但你的代码毫无意义。

你说......

Dim CompanyMaster_tbl 
As DataTable = Nothing <-- (here CompanyMaster_tbl set to null)


        For Each CompanyMaster_row As DataRow 
       In CompanyMaster_tbl.Rows <-- you are trying to referencing it.

所以，它肯定会抛出你的空引用异常。

而不是说...

For Each CompanyMaster_row As DataRow In CompanyMaster_tbl.Rows

为什么不循环遍历gridview中的行，然后填充数据表

For Each DataGridViewRow gr In gv.Rows

      If gr.Cells("cmpny").Value <> "" Then
            sqlInsertT1 &= "Insert Into CompanyMaster_tbl(CompanyName) 
            Values ('" & gr.Cells("cmpny").Value & "');"
            Exetransaction(sqlInsertT1)
        End If
        Ccid = RecordID("Cid", "CompanyMaster_tbl", "CompanyName", 
        gr.Cells("cmpny").Value)
    Next

将数据从数据gridview保存到表获取错误：'对象引用未设置为对象的实例“

1 个答案: