Level 2.1 SQL Taskbook
Given the 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:
Display a list of unique cities where users live.
Find users with the maximum salary.
Display the names of users whose salary is above the average salary of all users.
Find the number of users registered in the current year.
Display a list of users whose names start with the letter 'A'.
