Options (SQL Studio) 
You
can start SQL
Studio from the command line. To do this, execute the program
SQLSTO, with options, if necessary (SQL Studio: SAP DB
7.4
®
Starting SQL
Studio).
...
1. Change to the directory in which the program sqlsto.exe is stored.
2.
Enter the
following command:
sqlsto
[<options>]

You want to specify the following user data as options: database operator and the name of the database instance on the local server:
sqlsto -u samplename,secret -d MK1
SQL Studio is called and a database session is created for the database user samplename, password secret, with the database instance MK1.