在日期之间选择数据 - “没有给出一个或多个必需参数的值”

Question

我已经使用以下代码从Microsoft Access数据库中提取数据以填充VB.NET中的Combobox

Private Sub PopulateList()
    If RBDura.Checked = True Then
        CmbTstNo.Items.Clear()
        myConnection.ConnectionString = connstring
        Try
            myConnection.Open()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
        str = "SELECT DISTINCT Test_Code FROM Table_Durability_Test WHERE Log_Date BETWEEN " & DtFrom.Text & " and " & DtTo.Text & ""
        cmd = New OleDbCommand(str, myConnection)
        dr = cmd.ExecuteReader
        While dr.Read()
            CmbTstNo.Items.Add(dr.Item(0))
        End While
        myConnection.Close()
        CmbTstNo.SelectedIndex = 0
    End If
End Sub

然而，当代码运行时，我收到错误“没有给出一个或多个必需参数的值”

请指导..

Answer 1

您拥有的SQL字符串是"SELECT DISTINCT Test_Code FROM Table_Durability_Test WHERE Log_Date BETWEEN " & DtFrom.Text & " and " & DtTo.Text & ""

如果使用SQL输入文本或字符串到数据库，必须用单引号包围每个文本条目，这样您的SQL字符串将如下所示：

SELECT DISTINCT Test_Code FROM Table_Durability_Test WHERE Log_Date BETWEEN 'Value of DtFrom.Text' and 'Value of DtTo.Text'

请注意，我已使用单引号包围了Value of DtTo.Text和Value of DtFrom.Text。