I'm sorry if this question have posted before, i was googling stackoverflow but the result is NULL. 
I would create a login authentication using php, The requirement is : one username account can't login at the same time, if this occur the first login user should be logout automatically. Just like yahoo messenger do. How is the concept actually ?, What the best trick to do this with PHP ? Thank you so much.
I would create a login authentication using php, The requirement is : one username account can't login at the same time, if this occur the first login user should be logout automatically. Just like yahoo messenger do. How is the concept actually ?, What the best trick to do this with PHP ? Thank you so much.