atheus PHP Progress

I learned basics of JS, JQuery, HTML and CSS.
Now PHP. This is what I've learned so far. 
Please let me know if you've any beginner ideas that I can work on.

1. Variables.
2. Data Types.
3. Operators
4. String
5. If else statements
6. Else if
7. Switch case
8. String
9. Array
10. $POST[] array.
11. Functions
12. Redirections using header() method.
13. Do while Loop
14. While loop
15. Foreach loop
16. For Loop
17. HTML forms
18. Constant.
19. Include() Function
20. Isset() Function
21. Strlen() Functions
22. Strpos() Function
23. Strip_tags() Function
24. Mail Function
25. Empty() Function
26. Filter_var() function.

MySql Basics
What's a query?
Query is a request.

What does a query do?
A query requests something from database.