9. Find the employee numbers of all employees whose department is located in Seattle.

10. Find the last and first names of all employees who entered their projects on 04.01.2017.

11. Group all departments using their locations.

12. What is a difference between the DISTINCT and GROUP BY clauses?

13. How does the GROUP BY clause manage the NULL values? Does it correspond to the general treatment of these values?

14. What is the difference between COUNT(*) and COUNT(column)?

15. Find the highest employee number.

16. Get the jobs that are done by more than two employees.

17. Find the employee numbers of all employees who are clerks or work for department d3.

all in sql

emp_frame Matthew dept_no d1 Ann dept_name Research Accounting Marketing location Dallas Seattle Dallas emp_no 25348 10102 18316 29316 2581 9031 28559 emp_Iname Smith Jones Barrimore James Hansel Bertoni dept_no d3 d3 di d2 d2 d2 John James Elke d3 Elsa Sybill d2 di Moser Table 1-1 The department Table Table 1-2 The employee Table project_no project_name pl Apollo p2 Gemini p3 Mercury budget 120000 95000 186500 project_no P1 P3 emp_no 10102 10102 25348 18316 29346 2581 9031 28559 28559 P2 P2 P2 P3 Table 1-3 The project Table job Analyst Manager Clerk NULL NULL Analyst Manager NULL Clerk Clerk Clerk enter_date 2016.10.1 2018.1.1 2017.2.15 2017.6.1 2016.12.15 2017.10.15 2017.4.15 2017.8.1 2018.2.1 2016.11.15 2017.14 PI PI P2 P3 9031 29346 PI Table 1-4 The works_on Table