Concatenating problem

Hello,

I'm wondering if it is possible to concatenate values from different records. For instance, if I have a table that looks like this:

(first column is a customerNumber, second column is the orderNumber)
01 22
02 35
02 36
02 39
03 45
03 52

And I want a table that concatenates the OrderNumber values for each customer like this:

(first column is a customerNumber, second column is a concatenated orderNumber field)
01 22
02 35, 36, 39
03 45, 52

Is there an Excel function for something like this? Would I need to write my own function?

Thank you.