How to connect to SQL Server from command prompt with Windows authentication

You can use different syntax to achieve different things. If it is windows authentication you want, you could try this:

sqlcmd /S  /d  -E

If you want to use SQL Server authentication you could try this:

sqlcmd /S  /d -U -P 

Definitions:

/S = the servername/instance name. Example: Pete's Laptop/SQLSERV
/d = the database name. Example: Botlek1
-E = Windows authentication.
-U = SQL Server authentication/user. Example: Pete
-P = password that belongs to the user. Example: 1234

Hope this helps!

Try This :

--Default Instance

SQLCMD -S SERVERNAME -E

--OR
--Named Instance

SQLCMD -S SERVERNAME\INSTANCENAME -E

--OR

SQLCMD -S SERVERNAME\INSTANCENAME,1919 -E

More details can be found here