Question

我有一个包含以下列的表

ID(integer)
mat_id(integer)
move_date(Date/Time)
rec_num (Short text)
Qty (number(double))

我以编程方式建立了连接并尝试了一个查询代码如下

Public Class ViewMatInfo
    Dim ConStr As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\RMM\RMMDB.mdb;Persist Security Info=True"
    Dim Conn As New OleDb.OleDbConnection(ConStr)
    Dim ShowTable As New OleDb.OleDbCommand
    Dim RAD As OleDb.OleDbDataReader
 Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Try
            ShowTable.Connection = Conn
            ShowTable.CommandType = CommandType.Text
            ShowTable.CommandText = "SELECT Sum(qty) AS [totqty] FROM moves WHERE [mat_id] = " & MT_TEXT.SelectedValue.ToString & ""
            Conn.Open()
            RAD = ShowTable.ExecuteReader()
            While RAD.Read
                SUM_TEXT.Text = RAD.GetDouble("totqty")
            End While
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
        Try
            Me.MovesTableAdapter.FillByMat(Me.RMMDS.moves, MT_TEXT.SelectedValue)
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try

    End Sub
End Class

当我运行应用程序并从“MT_TEXT”组合框中选择材料时然后单击按钮所有材料移动都会大大填充数据网格视图。但SUM_TEXT文本框仍为空。并获取错误消息 “从字符串”totqty“转换为整数无效”

请问这个问题的解决方案

Answer 1

  = " & MT_TEXT.SelectedValue.ToString & ""

这看起来不确定。为什么最后有两个双引号，之前只有一个双引号。

该行应该是：

ShowTable.CommandText 
= "SELECT Sum(qty) AS [totqty] 
FROM moves WHERE [mat_id] = """ & MT_TEXT.SelectedValue.ToString & """"

MS Access和VB.net查询错误

1 个答案: