Killing Remote Application

Question:

I want to restrict a user from logging in different workstations or creating a multi-sessions of my application. HOw can I remotely kill the application if he tries to login again considering that he has still live connection or open application in the same pc or another? Assuming the user has successfully logged on to the other pc, how can I send a message to his original opened application informing that connection is closed or something like.

If you are familiar with Yahoo Messenger, you will understand my point.

Im using VB6 and MSSQL 2000...

Anybody who has an answer for this please help. As administrator, we normally prevent users from opening different sessions.

Assuming I can kill a live connection using KILL (sp_id) in SQL Server, In VB app, how can I test the connection if its alive or not coz I might use a timer to check every second or a minute so a message box will appear saying that connection is killed remotely and the application terminates?

declare @.@.user_id varchar(20)
set @.@.user_id='TheUserIDLogged'
sp_who @.@.user_id

I also tried to do this but error occurs:
Server: Msg 170, Level 15, State 1, Line 4
Line 4: Incorrect syntax near '@.@.user_id'.

How can i get the sp_id of this connection so that I can execute the
KILL function?

Any relevant idea is highly appreciated...ThanksHow do they login?

What's your security model?

And if you find multiple logins, which one do you pick to kill (Batai?)

USE Northwind
GO

CREATE TABLE tbl_sp_Who2 (
SPID int
, Status varchar(255)
, Login varchar(255)
, HostName varchar(255)
, BlkBy varchar(255)
, DBName varchar(255)
, Command varchar(255)
, CPUTime int
, DiskIO int
, LastBatch varchar(255)
, ProgramName varchar(255)
, SPID2 int)
GO

INSERT INTO tbl_sp_Who2 EXEC sp_who2 active

SELECT *
FROM tbl_sp_Who2
WHERE Login IN ( SELECT Login
FROM tbl_sp_Who2
GROUP BY Login
HAVING COUNT(*) > 1)
GO

DROP TABLE tbl_sp_Who2
GO

HTH|||After opening the initial connection, I would test to see if this user already has open connections using the sp_who command passing the login. If a connection exists, reply with a message box and terminate the application. To test to see if your application is already running on a computer you can test that within vb as well.|||Thanks for the effort...
BUt can you tell me further how to pass the login in SP_WHO so I can get its sp_id and then execute the KILL?
i tried this but an error occured...
declare @.@.user_id varchar(20)
set @.@.user_id='TheUserIDLogged'
sp_who @.@.user_id

Server: Msg 170, Level 15, State 1, Line 4
Line 4: Incorrect syntax near '@.@.user_id'.

Thanks in advance...