Not sure if this makes sense or not but here goes

I have 2 columns of information, the first one is a sku and the second is a description. The sku column has multiples of the same sku, each having a different description. What i need to do is combine the descriptions into one cell seperated by a character such as a comma or posibly html page breaks

SKU Description

1 a
2 a
1 b
2 b
2 c
2 d
1 c


so i need the results to look like

1 a,b,c
2 a,b,c,d

I only know some basic formulas and some random vba stuff but im just trying to figure out how to get this accomplished with a formula

Any help would be awesome Thanks

-Dan