SELECT * FROM "Friends"
SELECT * FROM "GameData"
SELECT * FROM "Item"
SELECT * FROM "Inventories"
SELECT * FROM "Stats"
SELECT * FROM "Types"
SELECT * FROM "Users"

--1.1:
SELECT * FROM "Users" WHERE email LIKE '%gmail.com'
--1.2:
UPDATE "Item" SET on_sale=true WHERE price<100 AND type_id=1
--1.3: 
DELETE FROM "Stats" WHERE id=2
--2.1: 
SELECT "Item".* FROM "Inventories"
JOIN "Users" on "Users".id="Inventories".user_id
JOIN "Item" on "Item".item_id="Inventories".item_id
WHERE username='manuser'
--2.2:
DELETE FROM "Item"
WHERE type_id=(
SELECT type_id FROM "Types" WHERE "Types".name='скин на оружие'
)
--2.3:
WITH T AS (SELECT friend_id FROM "Friends" WHERE user_id=(SELECT "Users".id FROM "Users" WHERE username='mainuser'))
SELECT "Users".* FROM "Users" JOIN T ON "Users".id=T.friend_id


INSERT INTO "Friends" values (2,1)
INSERT INTO "Users" values (3,'male@gmail.com', 'manuser','123','123')
INSERT INTO "Types" values (0,'лутбокс')
INSERT INTO "Types" values (1,'скин на оружие')
INSERT INTO "Item" values (3,'knifeskin.png',1,'500',true)
INSERT INTO "Inventories" values(0,1)
UPDATE "Item" SET item_id=1 where price=100