How to check number of db connections

just run this command:- (To check all DB_Connections)

SELECT
    DB_NAME(dbid) as DBName,
    COUNT(dbid) as NumberOfConnections,
    loginame as LoginName
FROM
    sys.sysprocesses
WHERE
    dbid > 0
GROUP BY
    dbid, loginame

And run this command:- (If you check specific database DB_Connections)

SELECT
    DB_NAME(dbid) as DBName,
    COUNT(dbid) as NumberOfConnections,
    loginame as LoginName
FROM
    sys.sysprocesses
WHERE
     DB_NAME(dbid) ='YourDBname'
GROUP BY
    dbid, loginame