1. SELECT DISTINCT wpis FROM zadania WHERE dataZadania <= '2020-07-07' AND wpis <> '';
2. SELECT dataZadania, wpis FROM zadania WHERE miesiac='lipiec';
3. SELECT miesiac, wpis FROM zadania WHERE wpis LIKE "S%";
4. UPDATE zadania SET wpis='Wycieczka nad morze' WHERE dataZadania = '2020-07-18';