在我正在从事的这个项目中，我必须使用SQL查询创建一堆饼图。
SQL有2个阶段
首先，我要收集在用户选择的时间范围内运行的计算机的名称，并将其放置在数据表中。
Dim query1 As String = String.Format("SELECT DISTINCT A.MacID FROM dbo.tblMachine A LEFT JOIN dbo.tblDataHdr b on a.MacID = b.MacID where DayID between '" & TextBox1.Text & "' AND '" & TextBox3.Text & "' ORDER BY A.MACID")
Dim dt1 As DataTable = GetData(query1)
在此示例中，我收集的计算机名称为
--------------
| MacId |
--------------
| A01 |
| A02 |
| C01 |
--------------
对于第二阶段，我想使用在第一阶段中收集的数据并将其引用到另一个SQL查询中。我的想法是将表中的内容转换为字符串，如下所示：
'A01', 'A02', 'C01'
这样，我只需要运行第二个SQL查询一次，而不必依赖For-Next语句来获取数据，这是我上次使用的结果，导致加载时间长，尤其是当有30多台机器。
如何获得此结果？我已经考虑了2天了，不知道如何开始。
编辑：
对于某些情况，这是我当前的代码。请忽略混乱。
Sub draw_chart1() 'All Machines
Dim check1, check2, fi, cnt
Dim seperator As String = ", "
Dim columnindex As Integer = 0
Dim myConnectionString As String = "Provider=SQLOLEDB;" & SQLDB_pp.ConnectionString
fi = 0
cnt = 0
PlaceHolder1.Dispose()
PlaceHolder2.Dispose()
'Get all machines
Dim query1 As String = String.Format("SELECT DISTINCT A.MacID FROM dbo.tblMachine A LEFT JOIN dbo.tblDataHdr b on a.MacID = b.MacID where DayID between '" & TextBox1.Text & "' AND '" & TextBox3.Text & "' ORDER BY A.MACID")
Dim dt1 As DataTable = GetData(query1)
Dim result As String = String.Join(seperator, dt1.AsEnumerable.Select(Function(r) "'" + r(columnindex).ToString() + "'")).TrimEnd(seperator.ToCharArray())
Dim dt As DataTable
Dim query As String
'Dim query As String = String.Format("SELECT Z.MacID, Z.EventName, ISNULL(DIFF,0) AS DIFF FROM (select distinct MacID, EventName from dbo.tblMachine a " _
' & "join (SELECT DISTINCT EVENTNAME FROM dbo.tblEvtDur where EventName <> 'ON' ) b on b.EventName <> '' and MacID in ('" & check1 & "') ) Z " _
' & "LEFT JOIN (SELECT A.MacID, A.EventName, SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) as diff,round(SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) / cast(aVG(Tdiff) " _
' & "as decimal(30,8)),4) * 100 AS PER FROM dbo.tblEvtDur A LEFT JOIN ( SELECT MacID, SUM(DATEDIFF(SECOND, STARTdt, eNDdt)) as Tdiff FROM dbo.tblEvtDur " _
' & "WHERE DayID between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' GROUP BY MacID ) B ON A.MacID = B.MacID WHERE DayID " _
' & "between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' AND A.MacID in ('" & check1 & "') group by A.MacID, A.EventName) a " _
' & "ON A.EVENTNAME = Z.EVENTNAME and Z.MacID = a.MacID order by Z.MacID, Z.EventName")
'Dim dt As DataTable = GetData(query)
'For q As Integer = 0 To dt1.Rows.Count - 1
'check1 = dt1.DataSet.ToString
'check1 = dt1.Rows(q)(0).ToString() '(0) means column, since query1 only search for 1 column, it uses 0 = 1ST COLUMN
query = String.Format("SELECT Z.MacID, Z.EventName, ISNULL(DIFF,0) AS DIFF FROM (select distinct MacID, EventName from dbo.tblMachine a " _
& "join (SELECT DISTINCT EVENTNAME FROM dbo.tblEvtDur where EventName <> 'ON' ) b on b.EventName <> '' and MacID in ({0}) ) Z " _
& "LEFT JOIN (SELECT A.MacID, A.EventName, SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) as diff,round(SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) / cast(aVG(Tdiff) " _
& "as decimal(30,8)),4) * 100 AS PER FROM dbo.tblEvtDur A LEFT JOIN ( SELECT MacID, SUM(DATEDIFF(SECOND, STARTdt, eNDdt)) as Tdiff FROM dbo.tblEvtDur " _
& "WHERE DayID between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' GROUP BY MacID ) B ON A.MacID = B.MacID WHERE DayID " _
& "between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' AND A.MacID in ({0}) group by A.MacID, A.EventName) a " _
& "ON A.EVENTNAME = Z.EVENTNAME and Z.MacID = a.MacID order by Z.MacID, Z.EventName", result)
dt = GetData(query)
'Next
'dt = GetData(query)
For a As Integer = 0 To dt.Rows.Count - 1
check2 = dt.Rows(a)(0).ToString()
Dim mychart As Chart = New Chart
Dim ChartArea1 As ChartArea = New ChartArea
Dim Legend1 As Legend = New Legend
'Dim dt As DataTable = GetData(query) '30 sec to process
Dim x As String() = New String(dt.Rows.Count - 1) {}
Dim y As Integer() = New Integer(dt.Rows.Count - 1) {}
For i As Integer = 0 To dt.Rows.Count - 1
x(i) = dt.Rows(i)(1).ToString()
y(i) = Convert.ToInt32(dt.Rows(i)(2))
Next
mychart.Width = 600
mychart.Height = 400
mychart.ChartAreas.Clear()
mychart.ChartAreas.Add("ChartArea2")
mychart.Series.Clear()
mychart.Series.Add(0)
mychart.Series(0).Points.DataBindXY(x, y)
mychart.Titles.Clear()
mychart.Titles.Add("[" & a + 1 & "] " & check2.ToString.ToUpper)
mychart.Titles(0).Font = New System.Drawing.Font("Tahoma", 12, System.Drawing.FontStyle.Bold)
mychart.Titles(0).BackColor = Color.PaleTurquoise
mychart.Titles(0).ForeColor = Color.Black
mychart.Series(0).ChartType = SeriesChartType.Pie
mychart.Series(0).LegendText = "#VALX"
mychart.Series(0)("BarLabelStyle") = "Center"
mychart.Series(0)("pointWidth") = "1"
mychart.Series(0).BorderDashStyle = ChartDashStyle.Solid
mychart.Series(0).BorderWidth = 2
mychart.Series(0).Label = "#PERCENT"
mychart.Series(0).ShadowColor = Color.Gray
mychart.Series(0).ShadowOffset = 10
mychart.Series(0).LabelBackColor = Drawing.Color.Cornsilk
mychart.Series(0).Font = New Font("Tahoma", 9, FontStyle.Bold)
mychart.Series(0).LegendToolTip = "#VALX - #PERCENT"
mychart.Series(0).ToolTip = "#VALX - #PERCENT"
mychart.ChartAreas("ChartArea1").Area3DStyle.Enable3D = True
mychart.Series(0).CustomProperties = "DrawingStyle=LightToDark"
'new
Chart1.Series(0).CustomProperties = "PieLabelStyle=Outside"
mychart.ChartAreas("ChartArea1").BorderDashStyle = BorderStyle.Solid
mychart.Palette = ChartColorPalette.None
mychart.Series(0).BorderDashStyle = ChartDashStyle.Solid
mychart.Series(0).BorderWidth = 2
mychart.Series(0).BorderColor = Color.Black
mychart.PaletteCustomColors = {Drawing.Color.Black, Drawing.Color.White, Drawing.Color.Blue, Drawing.Color.Yellow, Drawing.Color.Red, Drawing.Color.Orange, Drawing.Color.Green}
mychart.Legends.Clear()
mychart.Legends.Add(0)
mychart.Legends(0).Font = New Font("Tahoma", 10, FontStyle.Bold)
mychart.Legends(0).Docking = System.Web.UI.DataVisualization.Charting.Docking.Bottom
mychart.DataBind()
If (a + 1) Mod 2 <> 0 Then
PlaceHolder1.Controls.Add(mychart)
End If
If (a + 1) Mod 2 = 0 Then
PlaceHolder2.Controls.Add(mychart)
End If
Next
End Sub
Private Shared Function GetData(ByVal query As String) As DataTable
Dim dt As New DataTable()
Dim cmd As New SqlCommand(query)
' Dim constr As [String] = ConfigurationManager.ConnectionStrings("SQLDB_pp").ConnectionString
'Dim con As New SqlConnection(SQLDB_pp)
Dim sda As New SqlDataAdapter()
cmd.CommandType = CommandType.Text
cmd.Connection = SQLDB_pp
sda.SelectCommand = cmd
sda.Fill(dt)
Return dt
End Function
编辑2：
Dim sb As New StringBuilder()
sb.Append("SELECT Z.MacID, Z.EventName, ISNULL(DIFF,0) AS DIFF FROM (select distinct MacID, EventName from dbo.tblMachine a " _
& "join (SELECT DISTINCT EVENTNAME FROM dbo.tblEvtDur where EventName <> 'ON' ) b on b.EventName <> '' and MacID in (")
Dim params As New List(Of SqlParameter)()
Dim max As Integer = result.Length - 1
For i As Integer = 0 To max
If i = max Then
sb.Append("MacID" & i.ToString())
Else
sb.Append("MacID" & i.ToString() & ", ")
End If
params.Add(New SqlParameter("MacID" & i.ToString(), result(i)))
Next
sb.Append(") ) Z " _
& "LEFT JOIN (SELECT A.MacID, A.EventName, SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) as diff,round(SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) / cast(aVG(Tdiff) " _
& "as decimal(30,8)),4) * 100 AS PER FROM dbo.tblEvtDur A LEFT JOIN ( SELECT MacID, SUM(DATEDIFF(SECOND, STARTdt, eNDdt)) as Tdiff FROM dbo.tblEvtDur " _
& "WHERE DayID between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' GROUP BY MacID ) B ON A.MacID = B.MacID WHERE DayID " _
& "between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' AND A.MacID in (")
Dim params2 As New List(Of SqlParameter)()
Dim max2 As Integer = result.Length - 1
For j As Integer = 0 To max2
If j = max2 Then
sb.Append("MacID" & j.ToString())
Else
sb.Append("MacID" & j.ToString() & ", ")
End If
params2.Add(New SqlParameter("MacID" & j.ToString(), result(j)))
Next
sb.Append(") group by A.MacID, A.EventName) a " _
& "ON A.EVENTNAME = Z.EVENTNAME and Z.MacID = a.MacID order by Z.MacID, Z.EventName")
Dim q As String = sb.ToString()
编辑4：
这是我遇到问题的潜水艇的完整代码。这是原始代码，在第二次SQL加载时间较慢的情况下进行任何修改。
Sub draw_chart1() 'All Machines
Dim check1, check2, fi, cnt
Dim sql
Dim myConnectionString As String = "Provider=SQLOLEDB;" & SQLDB_pp.ConnectionString
fi = 0
cnt = 0
PlaceHolder1.Dispose()
PlaceHolder2.Dispose()
'Get all machines
Dim query1 As String = String.Format("SELECT DISTINCT A.MacID FROM dbo.tblMachine A LEFT JOIN dbo.tblDataHdr b on a.MacID = b.MacID where DayID between '" & TextBox1.Text & "' AND '" & TextBox3.Text & "' ORDER BY A.MACID")
Dim dt1 As DataTable = GetData(query1)
'Dim query As String = String.Format("SELECT Z.MacID, Z.EventName, ISNULL(DIFF,0) AS DIFF FROM (select distinct MacID, EventName from dbo.tblMachine a " _
' & "join (SELECT DISTINCT EVENTNAME FROM dbo.tblEvtDur where EventName <> 'ON' ) b on b.EventName <> '' and MacID in ('" & check1 & "') ) Z " _
' & "LEFT JOIN (SELECT A.MacID, A.EventName, SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) as diff,round(SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) / cast(aVG(Tdiff) " _
' & "as decimal(30,8)),4) * 100 AS PER FROM dbo.tblEvtDur A LEFT JOIN ( SELECT MacID, SUM(DATEDIFF(SECOND, STARTdt, eNDdt)) as Tdiff FROM dbo.tblEvtDur " _
' & "WHERE DayID between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' GROUP BY MacID ) B ON A.MacID = B.MacID WHERE DayID " _
' & "between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' AND A.MacID in ('" & check1 & "') group by A.MacID, A.EventName) a " _
' & "ON A.EVENTNAME = Z.EVENTNAME and Z.MacID = a.MacID order by Z.MacID, Z.EventName")
'Dim dt As DataTable = GetData(query)
For q As Integer = 0 To dt1.Rows.Count - 1
check1 = dt1.Rows(q)(0).ToString()
Dim query As String = String.Format("SELECT Z.MacID, Z.EventName, ISNULL(DIFF,0) AS DIFF FROM (select distinct MacID, EventName from dbo.tblMachine a " _
& "join (SELECT DISTINCT EVENTNAME FROM dbo.tblEvtDur where EventName <> 'ON' ) b on b.EventName <> '' and MacID in ('" & check1 & "') ) Z " _
& "LEFT JOIN (SELECT A.MacID, A.EventName, SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) as diff,round(SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) / cast(aVG(Tdiff) " _
& "as decimal(30,8)),4) * 100 AS PER FROM dbo.tblEvtDur A LEFT JOIN ( SELECT MacID, SUM(DATEDIFF(SECOND, STARTdt, eNDdt)) as Tdiff FROM dbo.tblEvtDur " _
& "WHERE DayID between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' GROUP BY MacID ) B ON A.MacID = B.MacID WHERE DayID " _
& "between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' AND A.MacID in ('" & check1 & "') group by A.MacID, A.EventName) a " _
& "ON A.EVENTNAME = Z.EVENTNAME and Z.MacID = a.MacID order by Z.MacID, Z.EventName")
Dim dt As DataTable = GetData(query) '47 sec to process
Dim mychart As Chart = New Chart
Dim ChartArea1 As ChartArea = New ChartArea
Dim Legend1 As Legend = New Legend
'Dim dt As DataTable = GetData(query) '30 sec to process
Dim x As String() = New String(dt.Rows.Count - 1) {}
Dim y As Integer() = New Integer(dt.Rows.Count - 1) {}
For i As Integer = 0 To dt.Rows.Count - 1
x(i) = dt.Rows(i)(1).ToString()
' y(i) = dt.Rows(i)(2).ToString()
y(i) = Convert.ToInt32(dt.Rows(i)(2))
Next
'Dim myConnection As New OleDbConnection(myConnectionString)
'Dim myCommand As New OleDbCommand(sql, myConnection)
'mychart.Width = Unit.Pixel(Session("sw") - 100)
'mychart.Height = Unit.Pixel((Session("sh") / 2) - 88)
mychart.Width = 600
mychart.Height = 400
mychart.ChartAreas.Clear()
mychart.ChartAreas.Add("ChartArea1")
mychart.Series.Clear()
mychart.Series.Add(0)
mychart.Series(0).Points.DataBindXY(x, y)
mychart.Titles.Clear()
mychart.Titles.Add("[" & q + 1 & "] " & check1.ToString.ToUpper)
mychart.Titles(0).Font = New System.Drawing.Font("Tahoma", 12, System.Drawing.FontStyle.Bold)
mychart.Titles(0).BackColor = Color.PaleTurquoise
mychart.Titles(0).ForeColor = Color.Black
mychart.Series(0).ChartType = SeriesChartType.Pie
' mychart.Series(0).Points.DataBindXY(x, y)
mychart.Series(0).LegendText = "#VALX"
mychart.Series(0)("BarLabelStyle") = "Center"
mychart.Series(0)("pointWidth") = "1"
mychart.Series(0).BorderDashStyle = ChartDashStyle.Solid
mychart.Series(0).BorderWidth = 2
mychart.Series(0).Label = "#PERCENT"
mychart.Series(0).ShadowColor = Color.Gray
mychart.Series(0).ShadowOffset = 10
mychart.Series(0).LabelBackColor = Drawing.Color.Cornsilk
mychart.Series(0).Font = New Font("Tahoma", 9, FontStyle.Bold)
'Chart1.Series(0).LabelToolTip = "#LABEL Percent: #PERCENT"
mychart.Series(0).LegendToolTip = "#VALX - #PERCENT"
mychart.Series(0).ToolTip = "#VALX - #PERCENT"
mychart.ChartAreas("ChartArea1").Area3DStyle.Enable3D = True
mychart.Series(0).CustomProperties = "DrawingStyle=LightToDark"
'new
Chart1.Series(0).CustomProperties = "PieLabelStyle=Outside"
mychart.ChartAreas("ChartArea1").BorderDashStyle = BorderStyle.Solid
mychart.Palette = ChartColorPalette.None
mychart.Series(0).BorderDashStyle = ChartDashStyle.Solid
mychart.Series(0).BorderWidth = 2
mychart.Series(0).BorderColor = Color.Black
mychart.PaletteCustomColors = {Drawing.Color.Black, Drawing.Color.White, Drawing.Color.Blue, Drawing.Color.Yellow, Drawing.Color.Red, Drawing.Color.Orange, Drawing.Color.Green}
mychart.Legends.Clear()
mychart.Legends.Add(0)
'Chart1.Legends(0).Enabled = True
''Chart1.Legends(0).BackColor = Drawing.Color.LightGreenplace
mychart.Legends(0).Font = New Font("Tahoma", 10, FontStyle.Bold)
mychart.Legends(0).Docking = System.Web.UI.DataVisualization.Charting.Docking.Bottom
'Chart1.Legends(0).Alignment = Drawing.StringAlignment.Center
'Chart1.Legends(0).BackColor = System.Drawing.Color.Transparent
mychart.DataBind()
'myplace.Visible = True
If (q + 1) Mod 2 <> 0 Then
PlaceHolder1.Controls.Add(mychart)
' Dim spacer As LiteralControl = New LiteralControl("<p />")
' PlaceHolder1.Controls.Add(spacer)
End If
'Exit For
If (q + 1) Mod 2 = 0 Then
PlaceHolder2.Controls.Add(mychart)
'Dim spacer As LiteralControl = New LiteralControl("<p />")
' PlaceHolder2.Controls.Add(spacer)
End If
Next
End Sub
答案 0 :(得分：1)
您可以使用String.Join()来连接所有DataTable列值，方法是先将DataTable列转换为字符串数组：
Dim dt1 As DataTable = GetData(query1)
Dim arr As String() = dt1.AsEnumerable().[Select](Function(x) x.Field(Of String)("MacId")).ToArray()
Dim result As String = String.Join(",", arr)
或使用此行：
Dim result As String = table.AsEnumerable().[Select](Function(x) x("MacId").ToString()).Aggregate(Function(a, b) String.Concat(a, "," & b))
之后，可以将输出字符串传递给具有表值参数的查询字符串，或者使用StringBuilder为ToArray()通过WHERE IN查询创建的字符串数组的每个元素添加参数：
Dim sb As New StringBuilder()
' example query string
sb.Append("SELECT * FROM TableName WHERE ColumnName IN (")
Dim cmd As New SqlCommand()
' note: array is zero-based
Dim max As Integer = arr.Length - 1
For i As Integer = 0 To max
If i = max Then
sb.Append("@MacId" & i.ToString())
Else
sb.Append("@MacId" & i.ToString() & ",")
End If
cmd.Parameters.AddWithValue("@MacId" & i.ToString(), arr(i))
Next
sb.Append(")")
Dim query As String = sb.ToString()
cmd.CommandText = query
' execute the query
更新：
由于查询是在函数内部执行的，因此需要将查询参数传递给函数：
Dim sb As New StringBuilder()
' example query string
sb.Append("SELECT * FROM TableName WHERE ColumnName IN (")
Dim params As New List(Of SqlParameter)()
For i As Integer = 0 To max
If i = max Then
sb.Append("@MacId" & i.ToString())
Else
sb.Append("@MacId" & i.ToString() & ",")
End If
params.Add(New SqlParameter("@MacId" & i.ToString(), arr(i)))
Next
sb.Append(")")
Dim query As String = sb.ToString()
dt = GetData(query, params)
功能内容
Private Shared Function GetData(ByVal query As String, Optional ByVal parameters As List(Of SqlParameter) = Nothing) As DataTable
Dim dt As New DataTable()
Dim cmd As New SqlCommand(query)
If parameter IsNot Nothing Then
cmd.Parameters.AddRange(parameters.ToArray())
End If
Dim sda As New SqlDataAdapter()
cmd.CommandType = CommandType.Text
cmd.Connection = SQLDB_pp
sda.SelectCommand = cmd
sda.Fill(dt)
Return dt
End Function
答案 1 :(得分：0)
您可以使用string.Join来对特定列的所有Rows值进行修补，并使用以下分隔符：", "（逗号+空格）。
< / p>
使用DataTable.Rows（DataRowCollection）作为源，使用LINQ Select()方法，可以将Rows[Column]内容转换为所需的字符串格式。
可能的结果：
Dim separator As String = ", "
Dim ColumnIndex as Integer = 0
Dim AllColumnValues As String = String.Join(separator,
dt1.Rows.OfType(Of DataRow).Select(Function(r) "'" + r(ColumnIndex).ToString() + "'"))
如果要引用System.Data.DataSetExtension程序集，则可以使用DataTable.AsEnumerable扩展名。代码可能会像这样更改：
Dim AllColumnValues As String = String.Join(separator,
dt1.AsEnumerable.Select(Function(r) "'" + r(ColumnIndex).ToString() + "'"))
如果某些值可以为null / empty，则可能需要添加一个Where()子句，以过滤null值：
Dim AllColumnValues As String = String.Join(separator,
dt1.AsEnumerable.Where(Function(r) Not r.IsNull(ColumnIndex)).
Select(Function(r) "'" + r(ColumnIndex).ToString() + "'"))
答案 2 :(得分：0)
最后，经过数小时的反复试验，我终于使字符串正常工作了。
自我说明：拥有GridView来检查DataTable内容是一个巨大的帮助。
现在我的代码基本上看起来像这样：
Dim query1 As String = String.Format("SELECT DISTINCT A.MacID FROM dbo.tblMachine A LEFT JOIN dbo.tblDataHdr b on a.MacID = b.MacID where DayID between '" & TextBox1.Text & "' AND '" & TextBox3.Text & "' ORDER BY A.MACID")
Dim dt1 As DataTable = GetData(query1)
Dim result As String = dt1.AsEnumerable().[Select](Function(x) x("MacId").ToString()).Aggregate(Function(a, b) String.Concat(a & "'" & "," & "'" & b))
Dim query As String = String.Format("SELECT Z.MacID, Z.EventName, ISNULL(DIFF,0) AS DIFF FROM (select distinct MacID, EventName from dbo.tblMachine a " _
& "join (SELECT DISTINCT EVENTNAME FROM dbo.tblEvtDur where EventName <> 'ON' ) b on b.EventName <> '' and MacID in ('" & result & "') ) Z " _
& "LEFT JOIN (SELECT A.MacID, A.EventName, SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) as diff,round(SUM(DATEDIFF(SECOND, A.STARTdt, A.eNDdt)) / cast(aVG(Tdiff) " _
& "as decimal(30,8)),4) * 100 AS PER FROM dbo.tblEvtDur A LEFT JOIN ( SELECT MacID, SUM(DATEDIFF(SECOND, STARTdt, eNDdt)) as Tdiff FROM dbo.tblEvtDur " _
& "WHERE DayID between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' GROUP BY MacID ) B ON A.MacID = B.MacID WHERE DayID " _
& "between '" & TextBox1.Text & "' and '" & TextBox3.Text & "' AND A.MacID in ('" & result & "') group by A.MacID, A.EventName) a " _
& "ON A.EVENTNAME = Z.EVENTNAME and Z.MacID = a.MacID order by Z.MacID, Z.EventName")
Dim dt As DataTable = GetData(query)
'Use this to help check the DataTable/Strings
GridView2.DataSource = dt 'change what you want to check accordingly
GridView2.DataBind()
通过使用GridView并将数据绑定到每个查询，确实可以帮助我了解数据的外观。 dt中显示的数据看起来很完美。
现在，我的下一个问题实际上是使用数据为每台计算机创建一个饼图。但我会在另一个问题中发帖。