SELECT * FROM `employee` WHERE SecondName IS NULL;
SELECT FirstName, IFNULL (SecondName, "brak"), LastName FROM `employee` WHERE 1;
SELECT Concat(FirstName, ' ', LastName) AS 'imie i nazwisko' FROM `employee` WHERE 1;
SELECT Name, CityId, AnnualIncome, EmployeeCount FROM `company` WHERE Street IS NOT NULL order by CityId, AnnualIncome DESC, EmployeeCount DESC;