Question

我正在尝试使用两个变量从winform执行更新查询，而不使用数据集。我分配了我的两个变量，然后运行查询，但它不断给出zcomp不是有效列名的错误。当然这是真的，但在我说= zcomp之前我告诉它哪一列。下面是我运行查询的代码。

Dim zamnt As Integer = WopartsDataGridView.Rows(e.RowIndex).Cells(e.ColumnIndex).Value
Dim zcomp As Integer = gridRow.Cells(0).Value

Dim con As New SqlConnection
Dim cmd As New SqlCommand
Try
  con.ConnectionString = "Data Source=MNT-MGR-2\SQLEX;Initial Catalog=MT;Integrated Security=True"
  con.Open()
  cmd.Connection = con
  cmd.CommandText = "UPDATE dbo.sparts SET [dbo.sparts.QtyonHand] = [dbo.sparts.QtyonHand] - zamnt WHERE [ComponentID] = zcomp"
  cmd.ExecuteNonQuery()
Catch ex As Exception
  MessageBox.Show("Error while updating record on table..." & ex.Message, "Update Records")
Finally
  con.Close()
  gridRow.Cells(4).Value = "Yes"
End Try

我尝试了几种不同的方法。如果我取出zamnt和zcomp并放入变量中的实际数值，它就可以正常工作。请帮助我整天都在搜索使用此更新查询的变量的方法。谢谢，斯泰西

Answer 1

您可能正在寻找如何在ADO.NET中使用参数。对于您的示例，它可能如下所示：

cmd.Parameters.Add("@zamnt", zamnt);
cmd.Parameters.Add("@zcomp", zcomp);

将这两行放在ExecuteNonQuery之前的任何位置。

由于参数需要@前缀，因此您还需要将查询更改为@zamnt而不是zamnt，而zcomp则相同：

cmd.CommandText = "UPDATE dbo.sparts SET [dbo.sparts.QtyonHand] = [dbo.sparts.QtyonHand] - @zamnt WHERE [ComponentID] = @zcomp"

Answer 2

除了使用参数之外，“Using”语句还会关闭连接并处理资源：

    Dim zamnt As Integer = WopartsDataGridView.Rows(e.RowIndex).Cells(e.ColumnIndex).Value
    Dim zcomp As Integer = gridRow.Cells(0).Value

    Try
        Using con As New SqlConnection("Data Source=MNT-MGR-2\SQLEX;Initial Catalog=MT;Integrated Security=True")
            con.Open()
            Using cmd As New SqlCommand
                cmd.CommandText = "UPDATE dbo.sparts SET [dbo.sparts.QtyonHand] = [dbo.sparts.QtyonHand] - @zamnt WHERE [ComponentID] = @zcomp"
                cmd.Parameters.AddWithValue("@zamt", zamnt)
                cmd.Parameters.AddWithValue("@zcomp", zcomp)
                cmd.ExecuteNonQuery()
            End Using
        End Using
    Catch ex As Exception
        MessageBox.Show("Error while updating record on table..." & ex.Message, "Update Records")
    Finally
        con.Close()
        gridRow.Cells(4).Value = "Yes"
    End Try

Answer 3

你试过这个吗？

Dim zamnt As Integer = WopartsDataGridView.Rows(e.RowIndex).Cells(e.ColumnIndex).Value
Dim zcomp As Integer = gridRow.Cells(0).Value

Dim con As New SqlConnection
Dim cmd As New SqlCommand
Try
  con.ConnectionString = "Data Source=MNT-MGR-2\SQLEX;Initial Catalog=MT;Integrated Security=True"
  con.Open()
  cmd.Connection = con
  cmd.CommandText = "UPDATE dbo.sparts SET [dbo.sparts.QtyonHand] = [dbo.sparts.QtyonHand] -" + zamnt + " WHERE [ComponentID] =" + zcomp
  cmd.ExecuteNonQuery()
Catch ex As Exception
  MessageBox.Show("Error while updating record on table..." & ex.Message, "Update Records")
Finally
  con.Close()
  gridRow.Cells(4).Value = "Yes"
End Try

带有VS2010 Winforms变量的where子句的SQL更新

3 个答案: