Sum values with Field Calculator, successive, cumulative

[StewartGalloway]

How can I sum values in a field for all records in the same group.  For all Site Number = A, return sum of SQ_FT into field SQ_FT_Total.  For all Site Number = B, return sum SQ_FT into field SQ_FT_Total.  Thanks.

[DanPatterson_Retired]

Why not produce a summary table rather than having the redundant values in the origin table?
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//005s00000055000000.htm

[StewartGalloway]

Thanks Dan that worked.  I used your link which suggested using Join on the resultant table.  Which I had to do in order to label each point with the total.  Thanks very much.

[DanPatterson_Retired]

No problem