Nested 'For Each Row' Loop

Hello! I’d like to ask for help in following problem.

I have an Excel file with multiple columns which I need to filter in a specific way. What I want to achieve is to keep only these rows which have the same values in selected columns.

Example table:

Name Surname DateBirth PlaceBirth Address City PostalCode
John Green 1981 NY Street1 City1 Code1
Chris Green 1981 LA Street2 City2 Code2
George Green 1980 LA Street3 City3 Code3
Andy Green 1981 NY Street4 City4 Code4
John Black 1980 NY Street5 City5 Code5
Andy Black 1981 NY Street6 City6 Code6
Andy Black 1981 NY Street7 City7 Code7
Andy Black 1980 NY Street8 City8 Code8
John Green 1981 NY Street9 City9 Code9

From the table above I need to drag out these rows where values for first 4 columns are the same. In this example the proper result would be 2 sets of data:




I tried to create DTs for each column, then clean it from duplicates and then use it in a ‘for each row’ for each of the column which I need to filter. Unfortunately, nesting it one in another doesnt work for more than 2 columns (my code in attachment)

. I’m sure there must be another way - please help

NestedLoop.xaml (21.3 KB) test.xlsx (9.7 KB)

The example input table you gave is very helpful. Can you do the same for the output(s) you wish to achieve? That will help us determine a solution

Here you goAndy_Black_1981_NY.xlsx (9.6 KB) John_Green_1981_NY.xlsx (9.7 KB)

Sorry, i didn’t see that was already included in your response. So if I understand correct, you want to pull ONLY if there are 2+ matches and if the item is unique, you don’t want it. Each of the matches you found should be put into it’s own datatable with the schema the exact same as the original table.

I will @ppr to see if he’ll reply as he’s a master with this. I’m not 100% sure it’s even possible and would have to fiddle around a lot to make it work, but I think you want to use LINQ to return an array of arrays of datarows (not a type, it’s an array of arrays). Then you can use a for each loop to iterate through the array of an array to clone the original datatable structure and add the datarows to the newly created datatable.

Of course a simpler method that is much less effecient would be to create a new column concatenating the first 4 columns, find all unique items (count = 1) to delete, then sort the datatable by your concatenated column. Then use a for each loop to check if the value equals the previous row. If it does, add it to the same datatable. If it doesn’t, add it to a new datatable

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As @Dave mentioned there is the concat trick even used within a groupBy or we constructing 4 keys by using the AND Concatenation (I did here,as other tricks are less easy to read/follow, also when it is posible).

find demo XAML here:
SplitGroups_4Col_IntoDT.xaml (9.3 KB)

Kindly note:

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Great, it works! Thanks a lot @ppr @Dave

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