数据集中的图表显示问题到具有多个系列的图表

Question

图表新手，这是我第一次尝试，所以开始吧。我已经根据 Separating Chart Series

中给出的答案构建了我的代码

我使用的图表仅经过修改以添加系列 2-7，并且还针对所有给定系列将系列类型从条形更改为样条。通过 GUI 进行的上述更改。

执行后，数据集正常获取，图表关键区域的系列名称更新显示正常，但图表本身不显示，除右侧颜色键外，仍为空白框。

数据类型：DateTime = DateTime，MCEC & AECC = Decimal，所有其他 = 整数

编辑：

第 2 天：尝试（多次）不同的代码尝试，最近一次尝试在每次更新图表（通过屏幕上的组合框）时擦除并重新建立系列，没有变化。
第 3 天：
- 进一步的替代代码尝试，最新迭代如下所示
- 尝试删除和添加新图表（完全未修改）
第 14 天：
- 自从我上次编辑以来已经尝试了大约 30 种不同的变体，但仍然没有成功。
- 已获得我认识的开发人员的帮助，尝试了他的代码变体（如下），但我们都遇到了困难。变体代码会显示一对图表，但上面没有显示任何系列。在这一点上，我正在寻找一个插件，希望能完成这项工作。

第 14 天代码：

Private Sub T3UpdateDisplay()
    '/////////////////////////////////
    'Query database and display results in the chart
    '/////////////////////////////////
    'build sql for processing
    sql = "SELECT DateTime, AECCRate1 AS AECC, MCECRate1 AS MCEC, Manila, Gosnell, Lepanto, Reginold, Promised_Land " _
     & "FROM pt_demand WHERE DateTime BETWEEN '" & ReportStart.ToString & "' AND '" & ReportEnd.ToString & "' " _
     & "ORDER BY DateTime ASC;"

    SetUpChart()
    GetAllDemands()

End Sub

Private Sub SetUpChart()

    Chart1.Series.Clear()
    Chart1.ChartAreas.Clear()

    Chart1.Series.Add("AECC")
    Chart1.ChartAreas.Add("AD")
    Chart1.Series("AECC").ChartArea = "AD"

    Chart1.Series.Add("MCEC")
    Chart1.ChartAreas.Add("MD")
    Chart1.Series("MCEC").ChartArea = "MD"

    Chart1.Series.Add("Manila")
    Chart1.ChartAreas.Add("M")
    Chart1.Series("Manila").ChartArea = "M"

    Chart1.Series.Add("Gosnell")
    Chart1.ChartAreas.Add("G")
    Chart1.Series("Gosnell").ChartArea = "G"

    Chart1.Series.Add("Lepanto")
    Chart1.ChartAreas.Add("L")
    Chart1.Series("Lepanto").ChartArea = "L"

    Chart1.Series.Add("Reginold")
    Chart1.ChartAreas.Add("R")
    Chart1.Series("Reginold").ChartArea = "R"

    Chart1.Series.Add("PromisedLand")
    Chart1.ChartAreas.Add("P")
    Chart1.Series("PromisedLand").ChartArea = "P"

    Chart1.Series("AECC").Color = Color.Green
    Chart1.Series("MCEC").Color = Color.Blue
    Chart1.Series("Manila").Color = Color.Red
    Chart1.Series("Gosnell").Color = Color.Gray
    Chart1.Series("Lepanto").Color = Color.Purple
    Chart1.Series("Reginold").Color = Color.Orange
    Chart1.Series("PromisedLand").Color = Color.Yellow

    Chart1.Series("AECC").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
    Chart1.Series("MCEC").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
    Chart1.Series("Manila").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
    Chart1.Series("Gosnell").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
    Chart1.Series("Lepanto").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
    Chart1.Series("Reginold").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
    Chart1.Series("PromisedLand").ChartType = DataVisualization.Charting.SeriesChartType.FastLine

    Chart1.Series("AECC").XValueType = DataVisualization.Charting.ChartValueType.Time
    Chart1.Series("MCEC").XValueType = DataVisualization.Charting.ChartValueType.Time
    Chart1.Series("Manila").XValueType = DataVisualization.Charting.ChartValueType.Time
    Chart1.Series("Gosnell").XValueType = DataVisualization.Charting.ChartValueType.Time
    Chart1.Series("Lepanto").XValueType = DataVisualization.Charting.ChartValueType.Time
    Chart1.Series("Reginold").XValueType = DataVisualization.Charting.ChartValueType.Time
    Chart1.Series("PromisedLand").XValueType = DataVisualization.Charting.ChartValueType.Time

End Sub

Private Sub GetAllDemands()
    'Connect to database do SQL for Dates Between
    On Error GoTo Err_Control
    Dim myDBCS As String = Main.DBCS    'create local copy of database connection string
    Dim ThisRecKey As Guid
    Dim sqlConnectionString As String = myDBCS

    Dim strGetDemandsSQL As String = sql
    Using sConnection As New SqlConnection(sqlConnectionString)
        sConnection.Open()
        Dim GetRecKeySQLCommand As New SqlCommand(strGetDemandsSQL, sConnection)
        'Get the Rec_Key
        Dim reader As SqlDataReader = GetRecKeySQLCommand.ExecuteReader()
        Dim ThisDateTime As Date

        While reader.Read()
            'Add Points
            Debug.Print(reader(0) & "    " & reader(1) & "    " & reader(2) & "    " & reader(3) & "    " & reader(4) & "    " & reader(5) & "    " & reader(6) & "    " & reader(7))
            ThisDateTime = reader(0)
            Chart1.Series("AECC").Points.AddXY(ThisDateTime.ToOADate(), CDbl(reader(1)))
            Chart1.Series("MCEC").Points.AddXY(ThisDateTime.ToOADate(), CDbl(reader(2)))
            Chart1.Series("M").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(3)))
            Chart1.Series("G").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(4)))
            Chart1.Series("L").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(5)))
            Chart1.Series("R").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(6)))
            Chart1.Series("P").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(7)))

        End While
        reader.Close()
        sConnection.Close()
    End Using

    Dim dblMin, dblMax As Double
    SetMinMax(dblMin, dblMax, "AECCRate1")
    Chart1.ChartAreas("AD").AxisY.Minimum = dblMin
    Chart1.ChartAreas("AD").AxisY.Maximum = dblMax
    Chart1.ChartAreas("AD").AxisX.Title = "AECC: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

    SetMinMax(dblMin, dblMax, "MCECRate1")
    Chart1.ChartAreas("MD").AxisY.Minimum = dblMin
    Chart1.ChartAreas("MD").AxisY.Maximum = dblMax
    Chart1.ChartAreas("MD").AxisX.Title = "MCEC: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

    SetMinMax(dblMin, dblMax, "Manila")
    Chart1.ChartAreas("M").AxisY.Minimum = dblMin
    Chart1.ChartAreas("M").AxisY.Maximum = dblMax
    Chart1.ChartAreas("M").AxisX.Title = "Manila: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

    SetMinMax(dblMin, dblMax, "Gosnell")
    Chart1.ChartAreas("G").AxisY.Minimum = dblMin
    Chart1.ChartAreas("G").AxisY.Maximum = dblMax
    Chart1.ChartAreas("G").AxisX.Title = "Gosnell: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

    SetMinMax(dblMin, dblMax, "Lepanto")
    Chart1.ChartAreas("L").AxisY.Minimum = dblMin
    Chart1.ChartAreas("L").AxisY.Maximum = dblMax
    Chart1.ChartAreas("L").AxisX.Title = "Lepanto: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

    SetMinMax(dblMin, dblMax, "Reginold")
    Chart1.ChartAreas("R").AxisY.Minimum = dblMin
    Chart1.ChartAreas("R").AxisY.Maximum = dblMax
    Chart1.ChartAreas("R").AxisX.Title = "Reginold: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

    SetMinMax(dblMin, dblMax, "Promised_Land")
    Chart1.ChartAreas("P").AxisY.Minimum = dblMin
    Chart1.ChartAreas("P").AxisY.Maximum = dblMax
    Chart1.ChartAreas("P").AxisX.Title = "Promised Land: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

Exit_Here:

    Exit Sub
Err_Control:
    Select Case Err.Number
        Case Else
            Resume Exit_Here
    End Select
End Sub

Private Sub SetMinMax(ByRef Min As Double, ByRef Max As Double, FieldName As String)
    On Error GoTo Err_Control
    Dim myDBCS As String = Main.DBCS    'create local copy of database connection string
    Dim sqlConnectionString As String = myDBCS
    Dim strGetMaxSQL As String = "Select MAX(" & FieldName & ") FROM pt_demand WHERE DateTime Between '" & ReportStart.ToString & "' AND '" & ReportEnd.ToString & "'"
    Dim strGetMinSQL As String = "Select MIN(" & FieldName & ") FROM pt_demand WHERE DateTime Between '" & ReportStart.ToString & "' AND '" & ReportEnd.ToString & "'"
    Using sConnection As New SqlConnection(sqlConnectionString)
        sConnection.Open()
        'MAX
        Dim GetMaxSQLCommand As New SqlCommand(strGetMaxSQL, sConnection)
        Dim readerMax As SqlDataReader = GetMaxSQLCommand.ExecuteReader()

        While readerMax.Read()
            Max = CDbl(CInt(readerMax(0) + (0.01 * readerMax(0))))
        End While
        readerMax.Close()
        'MIN
        Dim GetMinSQLCommand As New SqlCommand(strGetMinSQL, sConnection)
        'Get the Rec_Key
        Dim readerMin As SqlDataReader = GetMinSQLCommand.ExecuteReader()

        While readerMin.Read()
            Min = CDbl(CInt(readerMin(0) - (0.01 * readerMin(0))))
        End While
        readerMin.Close()

        sConnection.Close()
    End Using

Exit_Here:

    Exit Sub
Err_Control:
    Select Case Err.Number
        Case Else
            Resume Exit_Here
    End Select
End Sub

第 3 天代码在这里：

Private Sub T3UpdateDisplay()
            '/////////////////////////////////
    'Query database and display results in the chart
    '  borrowed from 
    '/////////////////////////////////
    'build sql for processing
    sql = "SELECT DateTime, MCECRate1 AS MCEC, AECCRate1 AS AECC, Manila, Gosnell, Lepanto, Reginold, Promised_Land " _
     & "FROM pt_demand WHERE DateTime BETWEEN '" & ReportStart.ToString & "' AND '" & ReportEnd.ToString & "' " _
     & "ORDER BY DateTime ASC;"

    '---- REMOVE FROM PRODUCTION ----
    'Main.Msg2User(sql, "query")

    Using ds = dbSelect_DataSet(sql)
        Chart1.Series.Clear()       'dump all series and recreate
        Chart1.Titles.Clear()       'dump title for recreation later

        Chart1.Titles.Add("System Demands: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm"))

        Dim mcec As New Series()
        mcec.ChartArea = "ChartArea1"
        mcec.Name = "MCEC"
        Chart1.Series.Add(mcec)
        Chart1.Series(mcec.Name).Color = Color.Green
        Chart1.Series(mcec.Name).ChartType = SeriesChartType.Spline
        Chart1.Series(mcec.Name).XValueMember = "DateTime"
        Chart1.Series(mcec.Name).XValueType = ChartValueType.DateTime
        Chart1.Series(mcec.Name).YValueMembers = "MCEC"
        Chart1.Series(mcec.Name).YValueType = ChartValueType.Double

        Dim aecc As New Series()
        aecc.ChartArea = "ChartArea1"
        aecc.Name = "AECC"
        Chart1.Series.Add(aecc)
        Chart1.Series(aecc.Name).Color = Color.DarkGray
        Chart1.Series(aecc.Name).ChartType = SeriesChartType.Spline
        Chart1.Series(aecc.Name).XValueMember = "DateTime"
        Chart1.Series(aecc.Name).XValueType = ChartValueType.DateTime
        Chart1.Series(aecc.Name).YValueMembers = "AECC"
        Chart1.Series(aecc.Name).YValueType = ChartValueType.Double

        Dim m As New Series()
        m.ChartArea = "ChartArea1"
        m.Name = "Manila"
        Chart1.Series.Add(m)
        Chart1.Series(m.Name).Color = Color.Blue
        Chart1.Series(m.Name).ChartType = SeriesChartType.Spline
        Chart1.Series(m.Name).XValueMember = "DateTime"
        Chart1.Series(m.Name).XValueType = ChartValueType.DateTime
        Chart1.Series(m.Name).YValueMembers = "Manila"
        Chart1.Series(m.Name).YValueType = ChartValueType.Int32

        Dim g As New Series()
        g.ChartArea = "ChartArea1"
        g.Name = "Gosnell"
        Chart1.Series.Add(g)
        Chart1.Series(g.Name).Color = Color.Gold
        Chart1.Series(g.Name).ChartType = SeriesChartType.Spline
        Chart1.Series(g.Name).XValueMember = "DateTime"
        Chart1.Series(g.Name).XValueType = ChartValueType.DateTime
        Chart1.Series(g.Name).YValueMembers = "Gosnell"
        Chart1.Series(g.Name).YValueType = ChartValueType.Int32

        Dim l As New Series()
        l.ChartArea = "ChartArea1"
        l.Name = "Lepanto"
        Chart1.Series.Add(l)
        Chart1.Series(l.Name).Color = Color.Red
        Chart1.Series(l.Name).ChartType = SeriesChartType.Spline
        Chart1.Series(l.Name).XValueMember = "DateTime"
        Chart1.Series(l.Name).XValueType = ChartValueType.DateTime
        Chart1.Series(l.Name).YValueMembers = "Lepanto"
        Chart1.Series(l.Name).YValueType = ChartValueType.Int32

        Dim r As New Series()
        r.ChartArea = "ChartArea1"
        r.Name = "Reginold"
        Chart1.Series.Add(r)
        Chart1.Series(r.Name).Color = Color.Orange
        Chart1.Series(r.Name).ChartType = SeriesChartType.Spline
        Chart1.Series(r.Name).XValueMember = "DateTime"
        Chart1.Series(r.Name).XValueType = ChartValueType.DateTime
        Chart1.Series(r.Name).YValueMembers = "Reginold"
        Chart1.Series(r.Name).YValueType = ChartValueType.Int32

        Dim p As New Series()
        p.ChartArea = "ChartArea1"
        p.Name = "Promised Land"
        Chart1.Series.Add(p)
        Chart1.Series(p.Name).Color = Color.Purple
        Chart1.Series(p.Name).ChartType = SeriesChartType.Spline
        Chart1.Series(p.Name).XValueMember = "DateTime"
        Chart1.Series(p.Name).XValueType = ChartValueType.DateTime
        Chart1.Series(p.Name).YValueMembers = "Promised_Land"
        Chart1.Series(p.Name).YValueType = ChartValueType.Int32

        Chart1.Size = New System.Drawing.Size(973, 467)
        'Chart1.BackColor = Color.WhiteSmoke
        Chart1.ChartAreas(0).AxisX.LabelStyle.Format = "MM/dd HH:mm"

        Chart1.DataSource = ds.Tables("pt_demand")
        Chart1.DataBind()
        Chart1.Visible = True

    End Using

End Sub

Answer 1

我仍然不完全确定为什么它在我尝试的前几次不起作用，但我怀疑次要数据类型差异之间可能存在问题（前两个系列是十进制，其余是整数）。

最终的解决方案（代码在下面）是针对两种不同类型的数据生成两个不同的图表，将图表保存到用户配置文件目录中的png，最后打出一个html文件来处理格式化、显示和打印需要，然后以编程方式打开文件。

以下示例代码仅包括：

Chart2的生成，因为它是两个图表中比较复杂的一个
适当设置图表 y 轴的过程，以及

将图表保存到磁盘的过程。

Imports System.Windows.Forms.DataVisualization.Charting
Imports System.IO

... ... ...

Dim myDBCS As String = Main.DBCS    'create local copy of database connection string
Dim myAPPFOLDER As String = Main.APPFOLDER  'local copy of scratchpad folder
Dim ReportStart, ReportEnd As DateTime  'reporting dates, persistent
Dim dblMin, dblMax As Double    'minimum and maximum values for y axis settings
Dim sql As String   'holds sql for construction & execute
Dim Chart1 As New Chart 'rate1 chart
Dim Chart2 As New Chart 'subs chart

... ... ...

Public Sub PTRSubs()
'/////////////////////////////////
'Build & execute SQL Query, Parse results, build chart
'/////////////////////////////////

'build sql
Dim cols As String = ""
sql = "SELECT DateTime, Gosnell, Lepanto, Manila, Reginold " _
  & "FROM pt_demand WHERE DateTime BETWEEN '" & ReportStart.ToString & "' AND '" & ReportEnd.ToString _
  & "' ORDER BY DateTime ASC;"

'/////////////////////////////////
'Setup Chart2
'if we're talking more than 1 day's worth of data, change the x axis type to datetime, otherwise, leave as time
Dim x As Boolean
If DateDiff(DateInterval.Day, ReportStart, ReportEnd) > 1 Then
    x = True
Else
    x = False
End If

Chart2.Size = New System.Drawing.Size(1280, 575)
Chart2.Series.Clear()
Chart2.ChartAreas.Clear()

Chart2.ChartAreas.Add("Subs")

'/////////////////////////////////
'define series parameters
Chart2.Series.Add("Gosnell")
Chart2.Series("Gosnell").ChartArea = "Subs"
Chart2.Series("Gosnell").Color = Color.Gray
Chart2.Series("Gosnell").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
Chart2.Series("Gosnell").XValueType = DataVisualization.Charting.ChartValueType.Time
If x = True Then
    Chart2.Series("Gosnell").XValueType = DataVisualization.Charting.ChartValueType.DateTime
Else
    Chart2.Series("Gosnell").XValueType = DataVisualization.Charting.ChartValueType.Time
End If

Chart2.Series.Add("Lepanto")
Chart2.Series("Lepanto").ChartArea = "Subs"
Chart2.Series("Lepanto").Color = Color.Purple
Chart2.Series("Lepanto").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
Chart2.Series("Lepanto").XValueType = DataVisualization.Charting.ChartValueType.Time
If x = True Then
    Chart2.Series("Lepanto").XValueType = DataVisualization.Charting.ChartValueType.DateTime
Else
    Chart2.Series("Lepanto").XValueType = DataVisualization.Charting.ChartValueType.Time
End If

Chart2.Series.Add("Manila")
Chart2.Series("Manila").ChartArea = "Subs"
Chart2.Series("Manila").Color = Color.Red
Chart2.Series("Manila").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
Chart2.Series("Manila").XValueType = DataVisualization.Charting.ChartValueType.Time
If x = True Then
    Chart2.Series("Manila").XValueType = DataVisualization.Charting.ChartValueType.DateTime
Else
    Chart2.Series("Manila").XValueType = DataVisualization.Charting.ChartValueType.Time
End If

Chart2.Series.Add("Reginold")
Chart2.Series("Reginold").ChartArea = "Subs"
Chart2.Series("Reginold").Color = Color.Orange
Chart2.Series("Reginold").ChartType = DataVisualization.Charting.SeriesChartType.FastLine
Chart2.Series("Reginold").XValueType = DataVisualization.Charting.ChartValueType.Time
If x = True Then
    Chart2.Series("Reginold").XValueType = DataVisualization.Charting.ChartValueType.DateTime
Else
    Chart2.Series("Reginold").XValueType = DataVisualization.Charting.ChartValueType.Time
End If

'/////////////////////////////////
'Connect to database, execute query
On Error GoTo Err_Control
Dim ThisRecKey As Guid
Dim strGetDemandsSQL As String = sql
Using sConnection As New SqlConnection(myDBCS)
    sConnection.Open()
    Dim GetRecKeySQLCommand As New SqlCommand(strGetDemandsSQL, sConnection)
    'Get the Rec_Key
    Dim reader As SqlDataReader = GetRecKeySQLCommand.ExecuteReader()
    Dim ThisDateTime As Date

    '/////////////////////////////////
    'build series datapoints
    While reader.Read()
        'Add Points
        Debug.Print(reader(0) & "    " & reader(1) & "    " & reader(2) & "    " & reader(3) & "    " & reader(4))
        ThisDateTime = reader(0)

        Chart2.Series("Gosnell").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(1)))
        Chart2.Series("Lepanto").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(2)))
        Chart2.Series("Manila").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(3)))
        Chart2.Series("Reginold").Points.AddXY(ThisDateTime.ToOADate(), CInt(reader(4)))

    End While
    reader.Close()
    sConnection.Close()
End Using

dblMin = 0
dblMax = 0

SetMinMax(dblMin, dblMax, "Gosnell")
If dblMax = 0 Then          'if axis min/max is not already set, then set both min and max based on these values them based on these values
    Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin
    Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax

Else
    If dblMin < Chart2.ChartAreas("Subs").AxisY.Minimum Then Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin 'only reset if value is lower than current setting
    If dblMax > Chart2.ChartAreas("Subs").AxisY.Maximum Then Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax 'only reset if value is higher than current setting

End If

SetMinMax(dblMin, dblMax, "Lepanto")
If dblMax = 0 Then          'if axis min/max is not already set, then set both min and max based on these values them based on these values
    Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin
    Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax

Else
    If dblMin < Chart2.ChartAreas("Subs").AxisY.Minimum Then Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin 'only reset if value is lower than current setting
    If dblMax > Chart2.ChartAreas("Subs").AxisY.Maximum Then Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax 'only reset if value is higher than current setting

End If

SetMinMax(dblMin, dblMax, "Manila")
If dblMax = 0 Then          'if axis min/max is not already set, then set both min and max based on these values them based on these values
    Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin
    Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax

Else
    If dblMin < Chart2.ChartAreas("Subs").AxisY.Minimum Then Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin 'only reset if value is lower than current setting
    If dblMax > Chart2.ChartAreas("Subs").AxisY.Maximum Then Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax 'only reset if value is higher than current setting

End If

SetMinMax(dblMin, dblMax, "Reginold")
If dblMax = 0 Then          'if axis min/max is not already set, then set both min and max based on these values them based on these values
    Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin
    Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax

Else
    If dblMin < Chart2.ChartAreas("Subs").AxisY.Minimum Then Chart2.ChartAreas("Subs").AxisY.Minimum = dblMin 'only reset if value is lower than current setting
    If dblMax > Chart2.ChartAreas("Subs").AxisY.Maximum Then Chart2.ChartAreas("Subs").AxisY.Maximum = dblMax 'only reset if value is higher than current setting

End If

'/////////////////////////////////
'set axis title
Chart2.ChartAreas("Subs").AxisX.Title = "Report window: " & Format(ReportStart, "yyyy/MM/dd HH:mm") & " to " & Format(ReportEnd, "yyyy/MM/dd HH:mm")

DumpChartToImage(Chart2, "Chart2")

Exit_Here:
Exit Sub

Err_Control:
Select Case Err.Number
    Case Else
        MsgBox("PTRSubs" & vbCrLf _
         & "Error Number: " & Err.Number.ToString & vbCrLf _
         & "Description:  " & Err.Description.ToString & vbCrLf _
         & "Source:  " & Err.Source, MsgBoxStyle.OkOnly, "errcontrol")
        Resume Exit_Here
End Select
End Sub

Private Sub SetMinMax(ByRef Min As Double, ByRef Max As Double, FieldName As String)
'/////////////////////////////////
'Get min and Max values of data from selected set
'/////////////////////////////////

On Error GoTo Err_Control

Dim strGetMaxSQL As String = "Select MAX(" & FieldName & ") FROM pt_demand WHERE DateTime Between '" & ReportStart.ToString & "' AND '" & ReportEnd.ToString & "'"
Dim strGetMinSQL As String = "Select MIN(" & FieldName & ") FROM pt_demand WHERE DateTime Between '" & ReportStart.ToString & "' AND '" & ReportEnd.ToString & "'"
Using sConnection As New SqlConnection(myDBCS)
    sConnection.Open()
    'MAX
    Dim GetMaxSQLCommand As New SqlCommand(strGetMaxSQL, sConnection)
    Dim readerMax As SqlDataReader = GetMaxSQLCommand.ExecuteReader()

    While readerMax.Read()
        Max = CDbl(CInt(readerMax(0) + (0.01 * readerMax(0))))
    End While
    readerMax.Close()
    'MIN
    Dim GetMinSQLCommand As New SqlCommand(strGetMinSQL, sConnection)
    'Get the Rec_Key
    Dim readerMin As SqlDataReader = GetMinSQLCommand.ExecuteReader()

    While readerMin.Read()
        Min = CDbl(CInt(readerMin(0) - (0.01 * readerMin(0))))
    End While
    readerMin.Close()

    sConnection.Close()
End Using

Exit_Here:
Exit Sub

Err_Control:
Select Case Err.Number
    Case Else
        Resume Exit_Here
End Select
End Sub

Private Sub DumpChartToImage(ByRef mychart As Chart, ByRef file As String)
'//////////////////////
'Save chart to file on disk, first wipe old copy if already exists
'//////////////////////
Dim filename As String = myAPPFOLDER & file & ".png"
If System.IO.File.Exists(filename) Then
    'The file exists, delete it first
    System.IO.File.Delete(filename)
    'recreate the file
    mychart.SaveImage(filename, System.Drawing.Imaging.ImageFormat.Png)

Else
    'the file doesn't exist, create it
    mychart.SaveImage(filename, System.Drawing.Imaging.ImageFormat.Png)

End If

End Sub

数据集中的图表显示问题到具有多个系列的图表

Chart display issue in dataset to chart with multiple series

vb.net

charts

dataset

series

graphing