Excel Comparison

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Posted on by saikrishnask1

I have two Excel files:

The first file contains 25,000 rows
The second file contains 250 rows

I need to compare these two files and extract the rows from the first file that are not present in the second file, then store the result in a new Excel file.

Although I can achieve this using the "For Each" and "If" activities, this method results in high time complexity. Additionally, if an error occurs midway, it becomes difficult to troubleshoot and handle.

Is there an alternative approach to achieve this efficiently, similar to how we use LINQ queries in UiPath, that reduces time complexity and simplifies the process?

Here i will give sample example:

Excel File 1:

ID	Name
1	Alice
2	Bob
3	Charlie
4	David
5	Eve

Excel File 2:

ID	Name
1	Alice
3	Charlie
5	Eve

Expected Output:

ID	Name
2	Bob
4	David

Categories:

Power Automate Desktop

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eetuRobo 4,204 Super User 2025 Season 2 on at

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I assume that you are running the flow from the Edit window? Running it from there is meant for only debugging and development. So even if you have Run delay set to 1ms it will still take much longer than if you run the flow Attended/Unattended or from the Power Automate Desktop "My flows" screen and just press "Run" on the flow

For example I have test flow that loops Excel file that has 5000 rows in it. It will take around 10 seconds to run the flow. But if I run it in Edit window it will take about 6 minutes (with run delay at minimum 1ms).

So consider running the flow from the Run button in the window where all your flows are.

Then you could add error handling that if error happens it adds LastError -variable (you get that by using "Get last error" -action) to a error list/datatable and the loop that failed. Then just continues to do the rest of the loop. And then in the end the error datatable or list you write into some text file named "ErrorList.txt".

Here is an example to get the idea. It tries to do the loop 3 times and if it goes to error 3 times then write the error on a txt file and goes to next loop item.

And this is how the error txt file looked like:

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VishnuReddy1997 2,656 Super User 2025 Season 2 on at

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Hey Hi,

Please try this below method as shown in images.

Code;

Please copy the below code to your flow.

Excel.LaunchExcel.LaunchAndOpenUnderExistingProcess Path: $'''C:\\Users\\Desktop\\Power Automate Desktop\\Practice\\Excel\\Community\\Excel1.xlsx''' Visible: True ReadOnly: False Instance=> ExcelInstance1 Excel.WriteToExcel.WriteCell Instance: ExcelInstance1 Value: $'''Tempo''' Column: $'''C''' Row: 1 Excel.LaunchExcel.LaunchAndOpenUnderExistingProcess Path: $'''C:\\Users\\Desktop\\Power Automate Desktop\\Practice\\Excel\\Community\\Excel2.xlsx''' Visible: True ReadOnly: False Instance=> ExcelInstance2 Excel.WriteToExcel.WriteCell Instance: ExcelInstance1 Value: $'''=VLOOKUP(B2,[Excel2.xlsx]Sheet2!$B:$B,1,0)''' Column: $'''C''' Row: 2 Excel.CopyCellsFromExcel.CopyCell Instance: ExcelInstance1 StartColumn: $'''C''' StartRow: 2 Excel.GetFirstFreeColumnRow Instance: ExcelInstance1 FirstFreeColumn=> FirstFreeColumn FirstFreeRow=> FirstFreeRow Excel.SelectCellsFromExcel.SelectCells Instance: ExcelInstance1 StartColumn: $'''C''' StartRow: 2 EndColumn: $'''C''' EndRow: FirstFreeRow - 1 MouseAndKeyboard.SendKeys.FocusAndSendKeysByInstanceOrHandle WindowInstance: ExcelInstance1 TextToSend: $'''{Control}({V})''' DelayBetweenKeystrokes: 10 SendTextAsHardwareKeys: False WAIT 2 Excel.ReadFromExcel.ReadAllCells Instance: ExcelInstance1 ReadAsText: False FirstLineIsHeader: True RangeValue=> ExcelData Variables.FindOrReplaceInDataTable.ReplaceItemInDataTableEverywhere DataTable: ExcelData AllMatches: True ValueToFind: -2146826246 MatchCase: False MatchEntireCellContents: True TextToReplaceWith: $'''NA''' DataTableMatches=> DataTableMatches Variables.FilterDataTable DataTable: ExcelData FilterParameters: { ^['RULE', 'COLUMN', 'OPERATOR', 'VALUE'], [$'''Or''', 2, $'''Equal''', $'''NA'''] } FilteredDataTable=> FilteredDataTable Variables.DeleteColumnFromDataTable.DeleteColumnWithIndex DataTable: FilteredDataTable ColumnIndex: 2 Excel.LaunchExcel.LaunchUnderExistingProcess Visible: True Instance=> ExcelInstance3 Excel.WriteToExcel.WriteCell Instance: ExcelInstance3 Value: FilteredDataTable.ColumnHeadersRow Column: $'''A''' Row: 1 Excel.WriteToExcel.WriteCell Instance: ExcelInstance3 Value: FilteredDataTable Column: $'''A''' Row: 2

(Note:- if you got your solution you can mark as solution and gives kudos)

Thanks & Regards
Vishnu Reddy

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