excel - PowerQuery: How can I concatenate grouped values?

Question

If I have the following table (shown in the image below), how can I write a grouped query that would concatenate the grouped results?

For this example, I'd want to group by the LetterColumn and concatenate the NumberColumn

So the desired results would be:

Answer 1

You can use the GUI to do it this way:

1. Select your LetterColumn and then Transform / GroupBy:

2. Select Add Column / Custom Column:

3. Click opposing arrows at top right of new AllData column to Extract Values from new AllData column:

   

4. Remove AllData column.