"concatenate" function?

[boball]

How can we concatenate column values from multiple rows into a single values.
Just like we have SUM to add column values from multiple rows, is there a way to concatenate the values instead?

More specifically, I want only unique values to come.
For example, if my rows are:
1 A
1 B
1 A
1 A
1 C
2 B
2 C
2 C
3 D

I want the output to be:
1 AB   (not ABAAC)
2 BC    (not BCC)
3 D

i.e. concatenate and show only unique values if there are repeats

[almeids]

Do you need actual concatenation or just the appearance?
You can use a master-detail pair of queries and a repeater within a list, but it won't be true concatenation (for example, if you run it to Excel each letter will appear in its own cell).
As far as suppressing the duplicates to show unique values, "Auto Group and Summarize" at the tabular level should take care of that for you.