Question

我正在构建一个VB.Net应用程序，以实时检查生产区域中的机器状态。我想在监视器中显示区域布局，如果机器状态为1，则将其设置为绿色，如果是2则为红色，如果是其他设置为橙色。我有以下代码，但它不起作用，因为它说操作员＆amp;没有为类型Control定义，我用它来声明我的标签数组。有人能告诉我，如果我做错了吗？（我是VB.Net的初学者）

 Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
                Dim labels() As Control = {Label1, Label2, Label3, Label4, Label5, Label6, Label7, Label8, Label9, Label10, Label11, Label12, Label13, Label14, Label15, Label16, Label17, Label18, Label19, Label20, Label21, Label22,
                    Label23, Label24, Label25, Label26, Label27, Label28, Label29, Label30, Label31, Label32, Label33, Label34, Label35, Label36, Label37, Label38, Label39, Label40, Label41, Label42, Label43, Label44, Label45, Label46,
                    Label47, Label48, Label49, Label50, Label51, Label52, Label53, Label54, Label55, Label56, Label57, Label58, Label59, Label60, Label61, Label62, Label63, Label64, Label65, Label66, Label67, Label68, Label69, Label70,
                    Label71, Label72}
                Dim estado As Integer

                Try
                    con.Open()
                    For i = 0 To 71
                        Console.WriteLine(labels(i))
                        Dim sqlquery = "select IDEstado from Maquinas where IDMaquina = " & labels(i) & ""
                        Dim myCommand As New MySqlCommand()
                        myCommand.Connection = con
                        myCommand.CommandText = sqlquery
                        Dim objReader As MySqlDataReader = myCommand.ExecuteReader
                        If objReader.Read = True Then
                            estado = objReader("IDEstado")

                            If estado = 1 Then
                                labels(i).BackColor = System.Drawing.Color.Green
                            ElseIf estado = 2 Then
                                labels(i).BackColor = System.Drawing.Color.Red
                            Else
                                labels(i).BackColor = System.Drawing.Color.DarkOrange
                            End If
                        End If
                        objReader.Close()
                    Next
                    con.Close()
                Finally
                End Try

            End Sub

Answer 1

你需要使用控件的Text属性，同时将其连接起来，就像下面你发布的代码一样，你实际上是在试图将字符串与控件连接起来，所以错误。

Dim sqlquery = "select IDEstado from Maquinas where IDMaquina = " & labels(i).Text & ""

Answer 2

您正在尝试使用sqlquery中的字符串连接Label控件，您需要从标签中获取文本，请参阅下文;

改变这个：

Dim sqlquery = "select IDEstado from Maquinas where IDMaquina = " & labels(i) & ""

到此：

Dim sqlquery = "select IDEstado from Maquinas where IDMaquina = " & labels(i).Text & ""

运营商'＆'没有为类型'String'和'Control'定义

2 个答案: