SqlDataReader 收集一行值而不是所有行？对 SqlDataReaders 感到困惑和陌生

Question

两个表：

CART（CartID、UserID、DateCreated、ProductID、ProductName、Size、Price、Quantity、Subtotal、HoursWork）

产品（产品 ID、名称、描述、价格、尺寸、图片、缩略图、重量、描述、库存、类别 ID、工时）

我正在尝试做的事情：根据 SELECT 语句选择的 all 类别 ID 显示两个按钮之一。

类别 ID 范围为 1-7。如果选择的任何类别 ID 匹配“1”、“2”或“7”，则应显示 'Create Booking' 按钮，否则应显示 'Delivery Option' 按钮。

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

       'Display the correct button:
    Dim conn As SqlConnection = New SqlConnection(ConnectionString)
    Dim cmd As SqlCommand = New SqlCommand
    cmd.CommandText = "SELECT products.CategoryID FROM Products INNER JOIN Cart on products.ProductID = cart.ProductID WHERE ([UserID] = @UserID) AND ([DateCreated] = CONVERT(date, GETDATE()))"

    Dim UserID As SqlParameter = New SqlParameter("@UserID", SqlDbType.NVarChar, 128)
    UserID.Value = "249f38b8-e745-44f4-8d78-806b0e5e7e0e"
    cmd.Parameters.Add(UserID)

    cmd.Connection = conn
    conn.Open()
    cmd.ExecuteNonQuery()

    Dim reader As SqlDataReader = cmd.ExecuteReader
    Dim CategoryID As Integer

    While reader.Read()
         'CategoryID = reader.GetValue(0)
    CategoryID = CType(reader("CategoryID"), Integer)
    End While
    conn.Close()

    lblTest.Text = CategoryID

    If CategoryID = "1" Or "2" Or "7" Then
            btnCreateBooking.Visible = True
        Else
            btnDeliveryOptions.Visible = True
        End If
End Sub

然而，购物车中last产品的CategoryID被SqlDataReader生成到label/variable，按钮'Create Booking'是只有连显示。

Answer 1

在这里找到答案：https://forums.asp.net/t/1401666.aspx?C+datareader+returning+multiple+rows+and+asp+Label+question+

If reader.HasRows Then
        While reader.Read()
            lblTest.Text = (lblTest.Text _
                + (reader("CategoryID").ToString + "<br>"))
        End While
        conn.Close()
    End If

并将我的 if 语句更正为：

If lblTest.Text.Contains("1") Or lblTest.Text.Contains("2") Or lblTest.Text.Contains("7") Then
        btnCreateBooking.Visible = True
    Else
        btnDeliveryOptions.Visible = True
        End If

SqlDataReader 收集一行值而不是所有行？对 SqlDataReaders 感到困惑和陌生

SqlDataReader collecting one row value instead of all rows? Confused & new to SqlDataReaders

asp.net

if-statement

sqldatareader