How to concatenate email addresses from different rows into 1 line with comma separator

I have a list like below

NAME	Email
Peter	peter@gmail.com
Peter	peter@yahoo.com
Mary	mary@yahoo.com

How can I make it to like below?

Peter	peter@gmail.com,peter@yahoo.com
Mary	mary@yahoo.com

Thanks!

by code, go here:
http://www.cpearson.com/Excel/stringconcatenation.aspx

by formula I'd do it like this (Assuming emails start from A1):
1. In B1 insert =A1
2. In B2 insert=B1&","&A2
3. Drag down B2 as far as needed

There's probably a simpler way but this works.

This involves a few steps but I've achieved what your after.

Assuming your list of names are in column A and the email addresses are in column B

First copy the list of names and remove any duplicates, fairly straight forward.

Then transpose the list of names (horizontally) starting at E1. Under the first name do a VLOOKUP

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where E$1 is your first name in the horizontal list (my short list of email addresses run from B1:B6, yours will probably be B1:B1000)

This will display the first email address for this person. Drag the formula down until you begin to see #N/A (we can remove these later along with the duplicates.)
repeat the process for the long list of names by dragging the formula underneath each name and down.

Now you have all the email address for each person below their name. Copy the entire range to a separate sheet and paste special (Values) and remove all formatting and duplicates.

Now for the concatenation.

Below the first column of names in an empty cell type:

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before you press enter, press F9. (you'll see the list of names in the formula bar.) Delete the curly brackets{} from the start and the end, and also the last comma on the last email address. Then enclose the string in normal brackets() and type concatenate before the first bracket like this

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Then press enter and you'll be left with this:

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You should then be able to drag this across for the list of names.

Hope this helps. Just an idea - had a 5 minutes to spare .

Dave

this seems not a simple method. remember I have more than 100000 records, in which there are around 8000 people, in those 8000 people some of them have more than 1 email addresses. Is it to use MATCH function to aggregate the email addresses belonged to same persons and concatenate the addresses in 1 line separated with comma or semi-colon? I attached my sample file in first post