One of my friends wanted to learn SQL server and queries. I provided him a few online books for basics. This may be helpful for someone.
If you want to learn queries than you must practice queries on your own. Microsoft's AdventureWorks is a really good sample database provided by Microsoft. Almost every online tutorial and videos use this database as an example.
here is the URL to download the Adventureworks Sample database. It also explains how to install etc.
Database objects like Schema, tables are explained here
some business scenarios explained here with Query.
This is one of the great online free tools to practice Queries on the database. It has a query sample and you can see the output. It also has some assessment.
Enjoy SQL queries.
In case of any questions then please ask in comments, I will try to reply to my best.