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条件表达式中的数据类型不匹配VB.NET中的错误

ms-access-2013 vb.net

-1

Boneyt · 技术社区 · 11 年前

嗨,我在VB中尝试以下代码时遇到了上述错误,我在表单上有3个文本框,用户输入股票代码后,我希望表单在相关文本框中输入匹配的产品组和产品描述。我使用的代码如下

Private Sub txt_productcode_Leave(sender As Object, e As EventArgs) Handles txt_productcode.Leave
    Dim dt As New DataTable
    Dim connstring As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:database
    Dim SqlString As String = "select [product group],[product description] from [stock] where [stock code] = " & txt_productcode.Text & ""
    Using conn As New OleDbConnection(connstring)
        Using command As New OleDbCommand(SqlString, conn)
            Using adapter As New OleDbDataAdapter(command)
                conn.Open()
                adapter.Fill(dt)
                conn.Close()
            End Using
            Dim MyDataRow As DataRow = dt.Rows(0)
            Dim x As Integer
            x = dt.Rows.Count
            For y = 0 To x - 1
                If y < x Then
                    MyDataRow = dt.Rows(y)
                    txt_productgroup.Text = MyDataRow("product group")
                    txt_productdescription = MyDataRow("product description")

                End If
            Next
        End Using
    End Using
End Sub

每次我尝试运行这个时,表单都会崩溃,我会得到上面的错误消息,代码中会突出显示以下行

adapter.Fill(dt)

有人能解释一下为什么这不起作用吗?谢谢

2 回复 | 直到 11 年前

Steve 11 年前

首先要做的是在构建命令文本并使用参数时删除字符串连接,然后为描述设置TextBox,而不是其文本属性。还删除了一些无用的代码

Private Sub txt_productcode_Leave(sender As Object, e As EventArgs) Handles txt_productcode.Leave
    Dim dt As New DataTable
    Dim connstring As String = "...."
    Dim SqlString As String = "select [product group],[product description] " & _
       "from [stock] where [stock code] = @stock"
    Using conn As New OleDbConnection(connstring)
        Using command As New OleDbCommand(SqlString, conn)
            Using adapter As New OleDbDataAdapter(command)
                conn.Open()
                command.Parameters.AddWithValue("@stock", txt_productcode.Text)
                adapter.Fill(dt)
            End Using
            For y = 0 To dt.Rows.Count - 1
                Dim MyDataRow = dt.Rows(y)
                txt_productgroup.Text = MyDataRow("product group").ToString()
                txt_productdescription.Text = MyDataRow("product description").ToString()

            Next
        End Using
    End Using
End Sub

stakx - no longer contributing Saravana Kumar 11 年前

很可能您的SQL语句包含错误。也许WHERE条件中缺少引号字符:

"â¦ WHERE [stock code] = '" + ... + "'"
'                       ^           ^

顺便说一句,由于使用简单的字符串连接而不是使用参数化查询来构建SQL命令,因此您的代码很容易受到SQL注入攻击。