What's the best way to learn SQL if it's hard to understand?

Question

MySQL

Good night everybody. Who can help with finding the best SQL learning material to understand? I studied SQL from video tutorials and an online tutorial, but unfortunately this language is hard for me to understand - I can make simple queries, but when compiling more complex ones, I already lose the thread of understanding what I'm doing, and compose it simply by examples . In the end, it may turn out that my complex query works, but does it in an inappropriate way. What can you watch or read to clarify for yourself the difficulties in understanding?

Answer 1

www.sql-ex.ru/?Lang=0 a resource specifically for, do all the exercises