How can you start SQL Server database Instance in different modes?

We can start SQL Server in different modes which are follows:-

1. Single User Mode (-m)
2. DAC (-A)
3. Emergency Mode 

• Single User Mode (-m): sqlcmd –m –d master –S PAXT3DEVSQL11 –c –U sa –P

• DAC (-A): sqlcmd –A –d master –S PAXT3DEVSQL11 –c –U sa –P

• Emergency Mode : ALTER DATABASE test_db SET EMERGENCY