在VB.Net中将大型数据表快速导出到Excel电子表格 [英] Fast Export of Large Datatable to Excel Spreadsheet in VB.Net
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问题描述
我在这里有一个有趣的难题，如何快速(在1分钟之内)将大数据表(由SQL填充，有35,000行)导出到Excel电子表格中供用户使用.我有可以处理导出的代码，虽然代码本身没有什么错误"，但导出整个文件要花4分钟的时间真是太慢了(如果用户的RAM较少或运行更多的代码有时会更长)他们的系统).遗憾的是，这是过去使用我们的旧方法花费的10分钟以上的改进.简而言之，如果不使用第三方组件，可以使其更快吗?如果是这样，怎么办?我的代码如下，减速发生在写入每行的消息框6和7之间.谢谢大家花时间来看看这个:
Private Sub btnTest_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnJeffTest.Click
Test(MySPtoExport)
End Sub
Private Sub Test(ByVal SQL As String)
'Declare variables used to execute the VUE Export stored procedure
MsgBox("start stop watch")
Dim ConnectionString As New SqlConnection(CType(ConfigurationManager.AppSettings("ConnString"), String))
Dim cmdSP As New SqlClient.SqlCommand
Dim MyParam As New SqlClient.SqlParameter
Dim MyDataAdapter As New SqlClient.SqlDataAdapter
Dim ExportDataSet As New DataTable
Dim FilePath As String
MsgBox("stop 1 - end of declare")
Try
' open the connection
ConnectionString.Open()
' Use the connection for this sql command
cmdSP.Connection = ConnectionString
'set this command as a stored procedure command
cmdSP.CommandType = CommandType.StoredProcedure
'get the stored procedure name and plug it in
cmdSP.CommandText = SQL
'Add the Start Date parameter if required
Select Case StDt
Case Nothing
' there's no parameter to add
Case Is = 0
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add("@StartDate", SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtStartDate.Text
End Select
MsgBox("stop 2 - sql ready")
'Add the End Date parameter if required
Select Case EdDt
Case Nothing
' there's no parameter to add
Case Is = 0
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add("@EndDate", SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtEndDate.Text
End Select
'Add the single parameter 1 parameter if required
Select Case SPar1
Case Is = Nothing
' there's no parameter to add
Case Is = ""
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add(SPar1, SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtSingleReportCrt1.Text
End Select
'Add the single parameter 2 parameter if required
Select Case Spar2
Case Is = Nothing
' there's no parameter to add
Case Is = ""
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add(Spar2, SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtSingleReportCrt2.Text
End Select
MsgBox("stop 3 - params ready")
'Prepare the data adapter with the selected command
MyDataAdapter.SelectCommand = cmdSP
' Set the accept changes during fill to false for the NYPDA export
MyDataAdapter.AcceptChangesDuringFill = False
'Fill the Dataset tables (Table 0 = Exam Eligibilities, Table 1 = Candidates Demographics)
MyDataAdapter.Fill(ExportDataSet)
'Close the connection
ConnectionString.Close()
'refresh the destination path in case they changed it
SPDestination = txtPDFDestination.Text
MsgBox("stop 4 - procedure ran, datatable filled")
Select Case ExcelFile
Case True
FilePath = SPDestination & lblReportName.Text & ".xls"
Dim _excel As New Microsoft.Office.Interop.Excel.Application
Dim wBook As Microsoft.Office.Interop.Excel.Workbook
Dim wSheet As Microsoft.Office.Interop.Excel.Worksheet
wBook = _excel.Workbooks.Add()
wSheet = wBook.ActiveSheet()
Dim dt As System.Data.DataTable = ExportDataSet
Dim dc As System.Data.DataColumn
Dim dr As System.Data.DataRow
Dim colIndex As Integer = 0
Dim rowIndex As Integer = 0
MsgBox("stop 5 - excel stuff declared")
For Each dc In dt.Columns
colIndex = colIndex + 1
_excel.Cells(1, colIndex) = dc.ColumnName
Next
MsgBox("stop 6 - Header written")
For Each dr In dt.Rows
rowIndex = rowIndex + 1
colIndex = 0
For Each dc In dt.Columns
colIndex = colIndex + 1
_excel.Cells(rowIndex + 1, colIndex) = dr(dc.ColumnName)
Next
Next
MsgBox("stop 7 - rows written")
wSheet.Columns.AutoFit()
MsgBox("stop 8 - autofit complete")
Dim strFileName = SPDestination & lblReportName.Text & ".xls"
If System.IO.File.Exists(strFileName) Then
System.IO.File.Delete(strFileName)
End If
MsgBox("stop 9 - file checked")
wBook.SaveAs(strFileName)
wBook.Close()
_excel.Quit()
End Select
MsgBox("File " & lblReportName.Text & " Exported Successfully!")
'Dispose of unneeded objects
MyDataAdapter.Dispose()
ExportDataSet.Dispose()
StDt = Nothing
EdDt = Nothing
SPar1 = Nothing
Spar2 = Nothing
MyParam = Nothing
cmdSP.Dispose()
cmdSP = Nothing
MyDataAdapter = Nothing
ExportDataSet = Nothing
Catch ex As Exception
' Something went terribly wrong. Warn user.
MessageBox.Show("Error: " & ex.Message, "Stored Procedure Running Process ", _
MessageBoxButtons.OK, MessageBoxIcon.Error)
Finally
'close the connection in case is still open
If Not ConnectionString.State = ConnectionState.Closed Then
ConnectionString.Close()
ConnectionString = Nothing
End If
' reset the fields
ResetFields()
End Try
End Sub
解决方案
就像使用VBA自动执行Excel一样，您可以将数组直接分配给Range对象的值:这是作为单个操作完成的，因此删除与跨越.Net代码和Excel实例之间的流程边界进行多次调用相关的开销.
例如，在此处查看已接受的答案:将数组写入Excel范围
I have an interesting conundrum here, how do I quickly (under 1 minute) export a large datatable (filled from SQL, 35,000 rows) into an Excel spreadsheet for users. I have code in place that can handle the export, and while nothing is "wrong" with the code per se, it is infuriatingly slow taking 4 minutes to export the entire file (sometimes longer if a user has less RAM or is running more on their system). Sadly, this is an improvement over the 10+ minutes it used to take using our old method. Simply put, can this be made any faster, without using 3rd party components? If so, how? My code is as follows, the slow down occurs between messageboxes 6 and 7 where each row is written. Thank you all for taking the time to take a look at this:
Private Sub btnTest_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnJeffTest.Click
Test(MySPtoExport)
End Sub
Private Sub Test(ByVal SQL As String)
'Declare variables used to execute the VUE Export stored procedure
MsgBox("start stop watch")
Dim ConnectionString As New SqlConnection(CType(ConfigurationManager.AppSettings("ConnString"), String))
Dim cmdSP As New SqlClient.SqlCommand
Dim MyParam As New SqlClient.SqlParameter
Dim MyDataAdapter As New SqlClient.SqlDataAdapter
Dim ExportDataSet As New DataTable
Dim FilePath As String
MsgBox("stop 1 - end of declare")
Try
' open the connection
ConnectionString.Open()
' Use the connection for this sql command
cmdSP.Connection = ConnectionString
'set this command as a stored procedure command
cmdSP.CommandType = CommandType.StoredProcedure
'get the stored procedure name and plug it in
cmdSP.CommandText = SQL
'Add the Start Date parameter if required
Select Case StDt
Case Nothing
' there's no parameter to add
Case Is = 0
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add("@StartDate", SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtStartDate.Text
End Select
MsgBox("stop 2 - sql ready")
'Add the End Date parameter if required
Select Case EdDt
Case Nothing
' there's no parameter to add
Case Is = 0
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add("@EndDate", SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtEndDate.Text
End Select
'Add the single parameter 1 parameter if required
Select Case SPar1
Case Is = Nothing
' there's no parameter to add
Case Is = ""
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add(SPar1, SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtSingleReportCrt1.Text
End Select
'Add the single parameter 2 parameter if required
Select Case Spar2
Case Is = Nothing
' there's no parameter to add
Case Is = ""
' there's no parameter to add
Case Else
'add the parameter name, it's direction and its value
MyParam = cmdSP.Parameters.Add(Spar2, SqlDbType.VarChar)
MyParam.Direction = ParameterDirection.Input
MyParam.Value = Me.txtSingleReportCrt2.Text
End Select
MsgBox("stop 3 - params ready")
'Prepare the data adapter with the selected command
MyDataAdapter.SelectCommand = cmdSP
' Set the accept changes during fill to false for the NYPDA export
MyDataAdapter.AcceptChangesDuringFill = False
'Fill the Dataset tables (Table 0 = Exam Eligibilities, Table 1 = Candidates Demographics)
MyDataAdapter.Fill(ExportDataSet)
'Close the connection
ConnectionString.Close()
'refresh the destination path in case they changed it
SPDestination = txtPDFDestination.Text
MsgBox("stop 4 - procedure ran, datatable filled")
Select Case ExcelFile
Case True
FilePath = SPDestination & lblReportName.Text & ".xls"
Dim _excel As New Microsoft.Office.Interop.Excel.Application
Dim wBook As Microsoft.Office.Interop.Excel.Workbook
Dim wSheet As Microsoft.Office.Interop.Excel.Worksheet
wBook = _excel.Workbooks.Add()
wSheet = wBook.ActiveSheet()
Dim dt As System.Data.DataTable = ExportDataSet
Dim dc As System.Data.DataColumn
Dim dr As System.Data.DataRow
Dim colIndex As Integer = 0
Dim rowIndex As Integer = 0
MsgBox("stop 5 - excel stuff declared")
For Each dc In dt.Columns
colIndex = colIndex + 1
_excel.Cells(1, colIndex) = dc.ColumnName
Next
MsgBox("stop 6 - Header written")
For Each dr In dt.Rows
rowIndex = rowIndex + 1
colIndex = 0
For Each dc In dt.Columns
colIndex = colIndex + 1
_excel.Cells(rowIndex + 1, colIndex) = dr(dc.ColumnName)
Next
Next
MsgBox("stop 7 - rows written")
wSheet.Columns.AutoFit()
MsgBox("stop 8 - autofit complete")
Dim strFileName = SPDestination & lblReportName.Text & ".xls"
If System.IO.File.Exists(strFileName) Then
System.IO.File.Delete(strFileName)
End If
MsgBox("stop 9 - file checked")
wBook.SaveAs(strFileName)
wBook.Close()
_excel.Quit()
End Select
MsgBox("File " & lblReportName.Text & " Exported Successfully!")
'Dispose of unneeded objects
MyDataAdapter.Dispose()
ExportDataSet.Dispose()
StDt = Nothing
EdDt = Nothing
SPar1 = Nothing
Spar2 = Nothing
MyParam = Nothing
cmdSP.Dispose()
cmdSP = Nothing
MyDataAdapter = Nothing
ExportDataSet = Nothing
Catch ex As Exception
' Something went terribly wrong. Warn user.
MessageBox.Show("Error: " & ex.Message, "Stored Procedure Running Process ", _
MessageBoxButtons.OK, MessageBoxIcon.Error)
Finally
'close the connection in case is still open
If Not ConnectionString.State = ConnectionState.Closed Then
ConnectionString.Close()
ConnectionString = Nothing
End If
' reset the fields
ResetFields()
End Try
End Sub
解决方案
As when using VBA to automate Excel, you can assign an array directly to the value of a Range object: this is done as a single operation, so you remove the overhead associated with making multiple calls across the process boundaries between your .Net code and the Excel instance.
Eg, see the accepted answer here: Write Array to Excel Range
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