如何删除此错误=“条件表达式中的数据类型不匹配” [英] how to remove this error="data type mismatch in criteria expression"

问题描述

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

        If Namount.Text = Nothing Then
            MsgBox("insert data first")

        Else

            Dim str, str1 As String

            str = "insert into customer values(" & Val(bill.Text) & ",'" & dtp.Value & "','" & cName.Text & "','" & Address.Text & "','" & paymenttype.Text & "'," & Val(phoneno.Text) & "," & Val(Tamount.Text) & "," & Val(Discount.Text) & "," & Val(Namount.Text) & ")"


            cmd = New OleDbCommand(str, cnn)
            dap = New OleDbDataAdapter(cmd)
            ds = New DataSet
            dap.Fill(ds)


            Dim i As Integer
            Dim Barcode, Item_name As String

            Dim Qty, item_rate, i_amt As String


            For i = 0 To DataGridView1.RowCount - 1
                Barcode = DataGridView1.Rows(i).Cells(0).Value
                Item_name = DataGridView1.Rows(i).Cells(1).Value
                Qty = DataGridView1.Rows(i).Cells(2).Value
                item_rate = DataGridView1.Rows(i).Cells(3).Value
                i_amt = DataGridView1.Rows(i).Cells(4).Value




                str1 = "insert into item values(" & bill.Text & ", " & Barcode & ", '" & Item_name & "'," & item_rate & "," & Qty & "," & i_amt & ")"

                cmd = New OleDbCommand(str1, cnn)
                dap = New OleDbDataAdapter(cmd)
                ds = New DataSet
                dap.Fill(ds)

            Next
            MessageBox.Show("Record Added")


            bill.Clear()
            paymenttype.ResetText()
            cName.Clear()
            Address.Clear()
            phoneno.Clear()
            DataGridView1.Rows.Clear()
            Tamount.Text = "00"
            Discount.Clear()
            Namount.Clear()
        End If

推荐答案

您必须将数据正确传递给SQL语句。你创建insert语句的方式可能是缺少引号（在不知道表格的情况下无法分辨），所以你会从中得到错误。



但是不要构造包含insert语句的 String ，而是使用预准备语句。这有几个优点：您不必担心数据类型，转义文本中的引号或SQL注入等内容。您可以在 MSDN [ ^ ]。

You'll have to pass the data correctly to your SQL statement. The way you've created your insert statement is probably missing quotes (can't tell without knowing what the table looks like), so you'll get the error from that.

But instead of constructing a String containing your insert statement, use a prepared statement. This has a couple of advantages: you don't have to worry about data types, escaping quotes in the text, or things such as SQL injection. You can find such an example at MSDN[^].

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