Show SQL Server open connections

-- Find the maximum number of user connections available on your system:
select @@max_connections as 'Max Connections';

-- See if your system has been restricted below the default limit
select name,
    value,
    value_in_use,
    [description]
from sys.configurations
where name = 'user connections';

-- Count Total Active Connections by Database
select db_name(dbid) as DatabaseName,
    count(dbid) as NumberOfConnections,
    loginame as LoginName
from sys.sysprocesses
where dbid > 0
group by dbid,
    loginame
order by NumberOfConnections desc;

-- View Detailed Connection Information (Modern DMVs)
select s.session_id,
    s.login_name,
    s.host_name,
    s.program_name,
    c.client_net_address,
    s.status,
    s.cpu_time,
    s.memory_usage
from sys.dm_exec_sessions as s
    inner join sys.dm_exec_connections as c on s.session_id = c.session_id
where s.is_user_process = 1
order by s.login_name, c.client_net_address;
-- Filters out background SQL Server system processes

-- Quick Session Summary
select count(*) as ActiveUserConnections
from sys.dm_exec_sessions
where is_user_process = 1;