How to find unused logins in SQL Server? I have a couple of databases on my server, each with its own users. Now I need to find and delete all those logins, which are not mapped to any user in any database. But I've also seen that it is possible that logins are not mapped to any user but they are able to do some operations because they have roles like sysadmin. So in this case those logins are in use. I want to know how can I find really not useful logins which are just left orphaned without any use? 

Thanks
I have something really ugly I made years ago. I just need to implement a dynamic SQL to automatically execute this "select". well here it goes:

First create this report table:

CREATE TABLE #REPORT ( [DATABASE] VARCHAR (MAX),[USER] VARCHAR (MAX))


Then execute this query and run it:

select 'use ['+name+'] '+char(13)+                                                       
'insert into #report                                                                     
            select db_name(db_id()) collate sql_latin1_general_cp1_ci_as as [database] , 
                   name collate sql_latin1_general_cp1_ci_as as [user]                   
    from sys.database_principals                                                         
        where type in (''s'',''u'')                                                      
            and name not in                                                              
                (''dbo'',''guest'',''information_schema'',''sys'')'+char(13)+char(13)    
from sys.databases                                                                       
    where name not in ('master','model','msdb','tempdb')


Then you can have:

--login without user
select name from sys.server_principals
    where name not in 
        (select [user] from #report)
        order by 1


AND

--user without login
select [database], [user] collate latin1_general_ci_as 
    from #report
        where [user] not in 
            ( select name collate latin1_general_ci_as
                from sys.server_principals)
order by 1