There are three ways to find who is connected to a database in sqlserver.
Use the SQL SERVER Management Studio — Management — Activity Monitor
This gives a list of users, database names, status, command, transactions, application with which they are using the database, CPU, IO and Memory usage, Login time etc.
Use the built in stored procedure called sp_who2
Run the command exec sp_who2
This gives a list of users, database names, status, command, program with which they are using the database, CPU time, Login time etc.
Use the script
select spid, status, loginame, hostname, blocked, db_name(dbid), cmd from master..sysprocesses where db_name(dbid) = ‘databasename’
User this also
select * from sys.dm_exec_sessions
This gives the status, login name and host name for the database.