MS Access - Rank of Values

I'm trying to produce rank values for data in a query, and can't find how to do it.

The help file mentions the RANK worksheet function, but this doesn't seem to be what I'm after, as it refers to both data and a data range - like the Excel function of the same name. This will not apply to data in a query.

I can produce rank values on a report, by using a running-sum of a text control of value 1, but this is no good for calculations.

Can anyone help?

If not, I'm going to have to export into Excel, generate the rank values, then update them back into a field in the data table.

Thanks.