SELECT product_id, product_type_id,
CASE product_type_id
WHEN 1 THEN 'Ksiazka'
WHEN 2 THEN 'VHS'
ELSE 'Czasopismo'
END
FROM Products;

-- idproduktu, nazwa, cena, jesli cena>15 cenawysoka, cena<15 cenaniska

SELECT product_id, name, price,
(CASE
WHEN price>15 THEN 'Wysoka cena'
WHEN price<15 THEN 'Niska cena'
END) Jaka_cena
FROM products;

-- SELECT TRANSLATE('Skąd', 'Wartość oreyginalna', 'Wartość zmieniona');

SELECT UPPER(last_name) FROM customers;
SELECT LOWER(last_name) FROM customers;
SELECT INITCAP(last_name) FROM customers;

-- Średnia cena dla produktu, pod uwage tylko ceny wyższe niz 15

SELECT TO_CHAR(AVG(CASE WHEN price>=15 THEN price END), '99D99') Cena FROM products;
SELECT TO_CHAR(4562.345646, '9999D99') FROM products;
SELECT * from customers;

UPDATE products
SET price=15
WHERE price<15;

SELECT last_name, TO_CHAR(dob, 'DD-MM-YYYY') FROM customers;

SELECT ADD_MONTHS(sysdate, 3) FROM dual;
SELECT NEXT_DAY(sysdate, 'Sobota') FROM dual;