1. Database I. Practice
SQL

2. Database Schema
hr.job_history (employee_id, start_date, end_date, job_id, department_id) hr.jobs (job_id, job_title, min_salary, max_salary) hr.departments (department_id, department_name, manager_id, location_id) hr.employees (employee_id, first_name, last_name, , phone_number, hire_date, job_id, salary, comission_pct, manager_id, department_id) hr.locations (location_id, street_address, postal_code, city, state_province, country_id) hr.countries (country_id, country_name, region_id)

3. Exercises
What is the telephone number and address of Mozhe Atkinson?
In which department does he work? (All attributes of the department in question should be returned.)
How much does he earn more than the minimal salary that he could get for his job?
What is the name of his manager?
What are the names of those employees who work in a department whose name contains letters a and s in arbitrary order?
What are the phone numbers of those employees who started their job after ?
What are the addresses of those emloyees who finished their job in March?

4. More Exercises…
What are the names of those employees who work in Brazil and earn as much money as can be earned in that job they profess.
What are the names of those employees who work in at least two different departments?
What are the names of those departments that have at least two employees?
What are those job titles that are professed in China but not in France?
What are the name of those employees who worked more than 500 days in a department without interruption?

5. Subqueries
What are the names of those departments that are located in Paris? (use IN)
What are the names of those employees who have a colleague working at the same department and earning the same salary? (use EXISTS)
What are the names of those departments, where everybody earns more than 1000 dollars? (use NOT IN)
What is the name of the employee who has the highest salary?
What are the names of those employees whose salary is greater than the lowest salary given for an employee?
What are the names of those employees who earns more than at least two other employees?
What is the name of that employee who has the second highest salary?

6. Aggregation How many employees work at the IT department?
What are the maximum and minimum salaries that are paid to an employee? (The result should contain a single row with two columns.)
Which job has the lowest minimum salary?
What is the name of that department, where the employees earn the most all together?
Who is that employee, who worked for the longest time in a department?
Which is the longest address?

7. Grouping
For each department give the number of employees, who work in the department in question and the average of the salaries of these employees.
Which is that city, where the most departments are located?
Which is that job, where the sum of the salaries is the highest?
Which are those jobs that are professed by at least five employees?
What are the names of those departments in which even the lowest salary is higher than 2000?