I think the AdventureWorks sample database contains the data and structures you can use to practice.

Check this courses on MVA- Microsoft Virtual Academy:

- Querying Microsoft SQL Server 2012 Databases Jump Start

- Querying with Transact-SQL

I think there are other courses also.

And there are some labs which might help, but I used the labs for 70-462 only.

Good luck!

Iulian