mysql - 计时器用 while 语句触发 mysql - 未获取所有数据

Question

我开发了一个winform，它需要不断地与mysql数据库联系，以确保所有“调用”都被获取并且是最新的 - 我遇到的问题是我的 ListView 每次计时器点击只填充1行。该计时器应该激活一个 while 语句，该语句应该处理所有数据，实际上还应该清除 ListView 以接收更新的数据。为什么我的 ListView 每次勾选只填充 1 个项目？

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    ListView2.Items.Clear()
    con.ConnectionString = "server=localhost;" _
& "user id=username;" _
& "password=password;" _
& "database=DMT"
        adptr = New MySqlDataAdapter("SELECT * , s.fid AS sfid, s.name AS sname, s.faddress AS sfaddress, s.fcity AS sfcity, s.fstate AS sfstate, s.fcontnumb AS sfcontnumb, s.fcontname AS sfcontname, s.fcontract AS sfcontract, d.fid AS dfid, d.name AS dname, d.faddress AS dfaddress, d.fcity AS dfcity, d.fstate AS dfstate, d.fcontnumb AS dfcontnumb, d.fcontname AS dfcontname, d.fcontract AS dfcontract FROM calls c LEFT JOIN facilities s ON c.Scene = s.fid LEFT JOIN facilities d ON c.Dest = d.fid WHERE putime < now( ) + INTERVAL 12 HOUR && Rdisp IS NULL ORDER BY putime desc", con)
    Try
        adptr.Fill(pendrun)
    Catch err As Exception
        Dim strError As String = "Exception: & err.ToString()"
    End Try
    If pendrun.Rows.Count > 0 Then
        While pop < pendrun.Rows.Count - 1
            TempStr(0) = pendrun.Rows(pop)("RID")
            Select Case pendrun.Rows(pop)("Utype")
                Case 1
                    TempStr(1) = "BLS Ambulance"
                Case 2
                    TempStr(1) = "ALS Ambulance"
                Case 3
                    TempStr(1) = "SCT Ambulance"
                Case 4
                    TempStr(1) = "Wheelchair Van"
                Case 5
                    TempStr(1) = "Taxi"
            End Select

            Select Case pendrun.Rows(pop)("Curgency")
                Case 1
                    TempStr(2) = "Scheduled"
                Case 2
                    TempStr(2) = "Non-Scheduled"
                Case 3
                    TempStr(2) = "ASAP"
                Case 4
                    TempStr(2) = "STAT"
            End Select
            TempStr(3) = pendrun.Rows(pop)("Pname")
            TempStr(4) = pendrun.Rows(pop)("Texttime")
            TempStr(5) = pendrun.Rows(pop)("sname") & " - " & pendrun.Rows(pop)("sfaddress") & ", " & pendrun.Rows(pop)("sfcity") & ", " & pendrun.Rows(pop)("sfstate")
            TempStr(6) = pendrun.Rows(pop)("dname") & " - " & pendrun.Rows(pop)("dfaddress") & ", " & pendrun.Rows(pop)("dfcity") & ", " & pendrun.Rows(pop)("dfstate")
            TempNode = New ListViewItem(TempStr)
            ListView2.Items.Add(TempNode)
            pop += 1
        End While
    End If

End Sub

我已经通过将计时器从 1 秒更改为 30 秒来验证它实际上直接链接到计时器(每个滴答 1 个项目)，并且它确实直接改变了这一点。

Answer 1

您的代码永远不会重置“pop”的值。我很确定这就是造成麻烦的原因。它每次tick 都会增加 1 个值，但永远无法执行所有这些操作，因为 pop 被设置为比 while 的最大值小 1。