MS Chart 使用兩條線做線圖...Multiple line

'假如是第二次載入

If Page.IsPostBack Then

Chart1.Visible = True

Dim date_s, date_e, type As String

Dim conn = New SqlConnection

Dim cmd As SqlCommand

Dim dr As SqlDataReader

Dim dt As DataTable = New DataTable

Dim SqlString As String

date_s = TextBox1.Text

date_e = TextBox2.Text

type = DropDownList1.SelectedValue

'date_s = "2013-08-21 16:48:00.000"

'date_e = "2013-08-21 17:50:00.000"

'type = "Co2"

conn.ConnectionString = System.Web.Configuration.WebConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString() '使用web config

SqlString = "select * from environment_log " & _

" where CONVERT (VARCHAR(10), timestamp, 111) >='" + date_s & _

"' and CONVERT (VARCHAR(10), timestamp, 111) <= '" + date_e & _

"' and type='" + type + "' order by timestamp"

'Label1.Text = SqlString

cmd = New SqlCommand(SqlString, conn) '定義cmnd為SqlCommand指令

'comnd.ExecuteNonQuery() '執行

Try

conn.Open() '開啟連結

dr = cmd.ExecuteReader() '讀取

If dr.HasRows = True Then

'第一種datareader 塞入datatable，使用多個線圖仍須測試

dt.Load(dr)

''Use linq to datatable

'Dim search1 = From c In dt.AsEnumerable() _

'Where c.Field(Of String)("DriverID") = "temp1" _

'Select c

'Dim temp1 = search1.CopyToDataTable()

'Dim search2 = From c In dt.AsEnumerable() _

'Where c.Field(Of String)("DriverID") = "temp2" _

'Select c

'Dim temp2 = search2.CopyToDataTable()

'Chart1.DataSource = temp2

'Chart1.Series("Series1").XValueMember = "timestamp"

'Chart1.Series("Series1").YValueMembers = "value"

''Chart1.Series("Series2").XValueMember = "timestamp"

''Chart1.Series("Series2").YValueMembers = "value"

'第二種使用databindcrosstable

'Use DataBindCrossTable

Chart1.DataBindCrossTable(dt.Rows, "DriverID", "timestamp", "value", "")

'不使用下列方式，只會跑長條圖..

For Each cs As Series In Chart1.Series

cs.ChartType = SeriesChartType.Spline

'cs.IsValueShownAsLabel = True

Next

Chart1.DataBind()

End If

Catch ex As Exception

Response.Write(e.ToString())

Finally

If Not (dr Is Nothing) Then ' --關閉 DataReader

cmd.Cancel() '--自己補上的，原因在下面有講。

dr.Close()

End If

If (conn.State = ConnectionState.Open) Then ' --關閉 DB的連線

conn.Close()

End If

End Try

End If