Where can I find exercises to practice SQL statements?

You can find some here as well.

SQL exercises or you can create a test table with fake data and manipulate that. Personally, I learn better with hands-on activity, by playing with the SELECT statements myself before even practicing an online guide. However, not everyone is the same.

Here are a few other links to check out:

• SQLCourse - Interactive for beginners.
• SQLCourse2 - It's awesome you can try and sharpen your skills.

Good luck.

Look the line of books by Celko, it has lots of examples and exercises.