I've managed to get thus far:

I've added my employer table and used a left join.

I can count all the users in total (sum of all users for that employer e.g. global users + superusers), but not just superusers.

using this code:

SELECT e.EmployerName, { fn IFNULL(x.super_userCnt, 0) } AS super_userCnt

FROM dbo.mytableEmployer e LEFT OUTER JOIN

(SELECT employerName, COUNT(*) AS super_userCnt

FROM employerSuper_Users

GROUP BY employerName) x ON e.EmployerName = x.employerName

if I add a where clause - it either says invalid column name or incorrect syntax