The default installation of SQLServer Express will create an Instance called:
computername\SQLEXPRESS
Installing SQL Server LocalDB 2012 via SambaPOS installation creates an Instance called:
(localdb)\V11.0
Installing SQL Server LocalDB 2014 via SambaPOS installation creates an Instance called:
(localdb)\MSSQLLocalDB
Installing SQL Server LocalDB manually (outside of SambaPOS installations) will by default create an instance called:
(localdb)\MSSQLLocalDB
It is good to keep in mind that an Instance is not the same thing as a Database. For example, my SQLEXPRESS Instance contains 7 Databases with the names like [SambaPOS3], [SambaPOS4], [SambaPOS5]. Though there is nothing wrong with, and nothing stopping you from renaming the Instance during installation to be SAMBAPOS… just know that the Instance is not the Database.
The SQL Server LocalDB versions do not install as a Service; instead they are simply a Process called sqlservr.exe, which you should see in the Task Manager.
If you are using SQLExpress, the Instance is shown in Services. Ensure it is set to Start Automatically.
If the Service is not shown as Started, then you have an issue with Service Startup in Windows, likely due to the way it is set to start or due to permissions.
If you are wanting to configure a multi-Terminal setup, you must use SQL Express because it supports multiple simultaneous connections, while LocalDB only allows 1 connection.
The connection string looks like this:
Data Source=INSTANCENAME; User Id=sa; Password=sambapos; Database=SambaPOS5