LocalDB SQL Server 2014 Express creates 2 instances (localdb)\ProjectsV12 & (localdb)\MSSQLLocalDB?

Question

I'm using SQL Server 2014 Express and the LocalDB option, and I have the following in my SQL Server object explorer pane in Visual Studio 2013...

So what is the difference between (localdb)\ProjectsV12 & (localdb)\MSSQLLocalDB?

Solution

The (localdb)\ProjectsV12 and (localdb)\ProjectsV13 instances are created by SQL Server Data Tools (SSDT) and should not be used by applications

(localdb)\MSSQLLocalDB is the SQL Server Express 2014/2016 LocalDB default instance name and an "automatic instance".

You can use the sqllocaldb.exe command line tool to manage which version (2014 or 2016) owns the MSSqlLocaldb instance

And (localdb)\v11.0 is the SQL Server 2012 LocalDB default instance name

Comments

[Dave]

Which one you should use for your local development db?

[ErikEJ]

One of the two last ones on the list

[Dave]

Is there a reason to not use ProjectsV12?

[ErikEJ]

It is not a deafault instance

[infiniteRefactor]

SSDT use ProjectsV12 instance for deploying database projects. This instance even might not exist if SSDT is not installed. Thus, using this instance name in connection strings is not recommended.

[gmail user]

This looks big mess to me created by MS. It is always misleading to me. I hope they make it clear and concise

[Edward Brey]

Follow-up questions on the purpose of the private instance