I've Created one Desktop Application which has server client access... Every user will has different login. Now the problem is, when one user is login, the same user cannot be login from other pc... The msg should come as the 'user is already Login'. In ASP.Net, it can be achieved through session.. But, how can I do this in Desktop Application. There is one solution.. We can maintain one log table for the logined users. But, that too will face deadlock situation.... Is any other solution for the single user login??

I think you are correct. You will have to create a log table which will maintain loginstatus. Deadlock situation can be avoid using Transaction. One problem which I think could be when the application closes abnormally which you will need to tackle in some intelligent way.

I think you are correct. You will have to create a log table which will maintain loginstatus. Deadlock situation can be avoid using Transaction. One problem which I think could be when the application closes abnormally which you will need to tackle in some intelligent way.

As your application is server-client based, you can have all clients to request server for login and let server decide whether to allow login or not.