Power Automate Desktop: Find One-to-Many Values Between Two Columns

The Problem

You have a table with two columns, A and B. You want to find every A value that is linked to more than one different B value.

✅ One-to-many	❌ Not one-to-many
Apple → Red, Green	Banana → Yellow, Yellow (same value repeated)
	Date → Brown (only one value)

No scripts needed. Only built-in Power Automate Desktop (PAD) actions.

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Sample Data

A	B
Apple	Red
Apple	Green
Banana	Yellow
Banana	Yellow
Cherry	Red
Cherry	Black
Date	Brown
Fig	Purple
Fig	Green
Grape	Purple

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How It Works (3 Simple Steps)

Step	What happens
1	Get the unique list of A values
2	For each A value, collect its unique B values
3	If there are more than 1 B values → add it to the result

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Variables Used

Variable	Type	Purpose
InputDT	Data table	Source data (A, B)
DistinctAValues	List	Unique A values
OneToManyResults	Data table	Final result
CurrentRow	Data row	Row being read (Step 1)
CurrentAValue	Text	A value being checked
BValuesForThisA	List	Unique B values for current A
DataRow	Data row	Row being read (Step 2)
BValuesText	Text	B values joined as "Red, Green"

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Build the Flow

Step 1 — Create the input table

Variables → Create new data table → add columns A and B → enter the sample rows → name it InputDT.

In real projects, use Excel → Read from Excel worksheet instead.

Step 2 — Get unique A values

Action	Setting
Create new list	Name: DistinctAValues
For each	Loop InputDT, item: CurrentRow
If	DistinctAValues Does not contain CurrentRow['A']
Add item to list	Add CurrentRow['A'] to DistinctAValues

Result: Apple, Banana, Cherry, Date, Fig, Grape

Step 3 — Create the result table

Variables → Create new data table → columns A Value and Matching B Values → name it OneToManyResults.

💡 The visual builder adds one empty row by default. Delete it in the builder (or add Clear data table right after) so your result doesn't start with a blank line.

Step 4 — Check each A value

Action	Setting
For each	Loop DistinctAValues, item: CurrentAValue
Create new list	Name: BValuesForThisA (inside the loop, so it resets each time)
For each	Loop InputDT, item: DataRow
If	DataRow['A'] Equal to CurrentAValue
If	BValuesForThisA Does not contain DataRow['B']
Add item to list	Add DataRow['B'] to BValuesForThisA
If	BValuesForThisA.Count Greater than 1
Join text	Join BValuesForThisA with ,  → BValuesText
Insert row into data table	Add [CurrentAValue, BValuesText] to OneToManyResults

Step 5 — Show the result

Message boxes → Display message → show OneToManyResults.

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Output

A Value	Matching B Values
Apple	Red, Green
Cherry	Red, Black
Fig	Purple, Green

Banana, Date and Grape are skipped. ✔️

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Quick Tips

Tip	Why
Create BValuesForThisA inside the loop	Otherwise old values carry over
Use %CurrentRow[0]% if no headers	Column index starts at 0
Good for small/medium tables	Nested loops slow down on thousands of rows

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Complete Code

Copy the code below and paste it directly into the PAD designer (Ctrl + V).

Variables.CreateNewDatatable InputTable: { ^['A', 'B'], [$'''Apple''', $'''Red'''], [$'''Apple''', $'''Green'''], [$'''Banana''', $'''Yellow'''], [$'''Banana''', $'''Yellow'''], [$'''Cherry''', $'''Red'''], [$'''Cherry''', $'''Black'''], [$'''Date''', $'''Brown'''], [$'''Fig''', $'''Purple'''], [$'''Fig''', $'''Green'''], [$'''Grape''', $'''Purple'''] } DataTable=> InputDT
Variables.CreateNewList List=> DistinctAValues
LOOP FOREACH CurrentRow IN InputDT
    IF NotContains(DistinctAValues, CurrentRow['A'], False) THEN
        Variables.AddItemToList Item: CurrentRow['A'] List: DistinctAValues
    END
END
Variables.CreateNewDatatable InputTable: { ^['A Value', 'Matching B Values'], [$'''''', $''''''] } DataTable=> OneToManyResults
LOOP FOREACH CurrentAValue IN DistinctAValues
    Variables.CreateNewList List=> BValuesForThisA
    LOOP FOREACH DataRow IN InputDT
        IF DataRow['A'] = CurrentAValue THEN
            IF NotContains(BValuesForThisA, DataRow['B'], False) THEN
                Variables.AddItemToList Item: DataRow['B'] List: BValuesForThisA
            END
        END
    END
    IF BValuesForThisA.Count > 1 THEN
        Text.JoinText.JoinWithCustomDelimiter List: BValuesForThisA CustomDelimiter: $''', ''' Result=> BValuesText
        Variables.AddRowToDataTable.AppendRowToDataTable DataTable: OneToManyResults RowToAdd: [CurrentAValue, BValuesText]
    END
END
Display.ShowMessageDialog.ShowMessage Title: $'''One-to-Many Results''' Message: OneToManyResults Icon: Display.Icon.None Buttons: Display.Buttons.OK DefaultButton: Display.DefaultButton.Button1 IsTopMost: False ButtonPressed=> ButtonPressed

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References

• Variables actions
• Loop actions
• Conditional actions
• Text actions
• Variable data types