aspnet_regsql.exe

GO to windows link

c:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_regsql.exe

sql/ visual stidio command promt type this

aspnet_regsql.exe -S <Server> -U <Username> -P <Password> -ed -d Northwind

other solution

aspnet_regsql -d <databasename> -ssadd -sstype c -U <username>