How can I get an accurate count of computers (workstations) logged in to my SQL Server database?

Question

We license our software by number of workstations.
I have a query that I have used for years to get an accurate count of the workstations logged in to my SQL Server database. For simplicity, all users use the same login name/password. This is built in to the script that attaches to the DB. They
have access only to that DB with the exception of
USE [Master] GRANT VIEW SERVER STATE to MyUser
The query that has been working is below:
Basically this relies on the mac address (Master.dbo.sysprocesses.net_addre
SELECT COUNT(Users) AS UserCount FROM (SELECT COUNT(Master.dbo.sysprocesses.hostname) AS Users FROM Master.dbo.sysprocesses LEFT OUTER JOIN Master.dbo.sysdatabases ON Master.dbo.sysdatabases.dbid = Master.dbo.sysprocesses.dbid WHERE (Master.dbo.sysdatabases.name = 'MyDatabase') GROUP BY Master.dbo.sysprocesses.net_address) AS UserCount_1
ss), since both Workstation names and ip addresses can be duplicated.
Recently this has stopped working at a number of customers. Suddenly individual workstations are showing multiple net addresses for the same workstation causing a substantial overcount of users. This may be related to SQL Server 2012 - not sure.
What I need is a very reliable way to get a count of workstations logged in to my database.
If anyone can tell me why I am suddenly getting multiple net_addresses for each workstation and how to prevent that that would be one possible solution.
Otherwise if anyone can give me a rock solid way to get a workstation count other than the above that would be great. Our largest customer is 50 users by the way.
Thanks in advance for any help.
Kim

Answer 1

I think your count is getting skewed because of duplicate rows in sysprocesses because of parallelism. Add DISTINCT to your query:
SELECT COUNT(Users) AS UserCount
FROM
( SELECT COUNT(DISTINCT Master.dbo.sysprocesses.hostname) AS Users
FROM Master.dbo.sysprocesses LEFT OUTER JOIN Master.dbo.sysdatabases
ON Master.dbo.sysdatabases.dbid = Master.dbo.sysprocesses.dbid
WHERE (Master.dbo.sysdatabases.name = 'MyDatabase'
GROUP BY Master.dbo.sysprocesses.net_address) AS UserCount_1
Satish Kartan www.sqlfood.com