1. Display the FIRST name AND JOIN DATE OF the employees who joined BETWEEN 2002 AND 2005.

SELECT employees.first_name, employees.HIRE_DATE
FROM employees
WHERE employees.HIRE_DATE >='01-JAN-2002' AND employees.HIRE_DATE<='31-DEC-2005';

2. Display FIRST name, salary, AND round the salary TO thousands.

SELECT employees.first_name, salary, round(employees.salary,-3)
FROM employees;

3. Display FULL name AND DATE OF FIRST salary OF the employees.

SELECT employees.First_name||' '||employees.last_name "Име Фамилия", ADD_MONTHS(employees.HIRE_DATE,1) "Първа заплата"
FROM employees;

4. Display employees who joined IN specific YEAR (your choice, pick a YEAR WITH records).

SELECT employees.First_name||' '||employees.last_name "Име Фамилия", employees.HIRE_DATE
FROM employees
WHERE to_char(hire_date,'YYYY')=&YEAR;

5. Display how many employees joined IN each MONTH OF the CURRENT YEAR.

SELECT to_char(hire_date,'MM'), COUNT(*)
FROM employees
WHERE to_char(hire_date,'YYYY')=&YEAR
GROUP BY to_char(hire_date,'MM')
ORDER BY to_char(hire_date,'MM');