How to see how many column(a) values are for each column(b) in SQL

Column(a) is a Id field. Now column(b) can have many column(a)s attached to one column(b). How can i write this query so i can return for example

column(b) | Total column(a)s

It would be something like the following:

Select [DCN-field], COUNT(woid) FROM wo
ORDER BY COUNT(DCN-field) DESC

Thanks!

SELECT [DCN-field], COUNT(woid) FROM wo
    GROUP BY [DCN-field]
    ORDER BY 2 DESC