选择日期之间的数据 - "No value given for one or more required parameters"

Question

我已将以下代码从 Microsoft Access 数据库中提取数据以填充 VB.NET

中的组合框

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，当代码为运行时，我得到一个错误 "No value given for one or more required parameters"

请指导..

Answer 1

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

如果您使用 SQL 向数据库输入文本或字符串，您必须用单引号将每个文本条目括起来，这样您的 SQL字符串看起来像这样：

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

请注意，我用 单引号 .

将 Value of DtTo.Text 和 Value of DtFrom.Text 括起来

选择日期之间的数据 - "No value given for one or more required parameters"

Selecting data between dates - "No value given for one or more required parameters"

vb.net

vb.net-2010

oledbcommand