SQL Taskbook Level 2.1
Given a table:
| id | name | salary | city | registration_date |
| 1 | Aaron | 4300.00 | New-York | 2023-02-10 |
| 2 | Marina | 2000.00 | Minsk | 2022-12-10 |
| 3 | Max | 1500.00 | Kyiv | 2020-05-30 |
| 4 | Catherine | 3000.00 | Berlin | 2023-10-02 |
| 5 | Andrew | 900.00 | Berlin | 2021-08-31 |
Solve the following tasks for it:
List the unique cities where users live.
Find users with the highest salary.
Display the names of users whose salary is higher than the average salary of all users.
Find the number of users registered in the current year.
List users whose names start with the letter 'A'.
