show me some easy tricks for SQL

Question

this is very hard for me.. I don't learn any single thing from here..

Answer 1

so what should be made better?

Answer 2

please explain about this thing.. how I can do this?

Answer 3

where is this topic "...easy Tricks for SQL" in the course? ... so i don't know what you want to explain

Answer 4

theres no trick in sql...