DB

CRUD	SQL 예시	SQLAlchemy 2.0 코드	결과 반환 메서드
SELECT All	SELECT * FROM users;	stmt = select(User)	db.scalars(stmt).all() (객체 리스트)
SELECT One	SELECT * FROM users WHERE id = 10;	stmt = select(User).where(User.id == 10)	db.scalars(stmt).one_or_none() (단일 객체 또는 None)
UPDATE	UPDATE users SET name = 'New Name' WHERE id = 10;	stmt = update(User).where(User.id == 10).values(name="New Name")	db.execute(stmt); db.commit(
DELETE	DELETE FROM users WHERE id = 10;	stmt = delete(User).where(User.id == 10)	db.execute(stmt); db.commit()
INSERT	INSERT INTO users (name) VALUES ('Dgeon');	new_user = User(name='Dgeon'); db.add(new_user); db.commit()	db.refresh(new_user) (ID 등을 위해)
INNER JOIN		stmt = select(User, Item).join(Item) select(User, Item).join(Item).where(User.name == Item.title)	db.execute(stmt).all() (튜플 리스트)
LEFT JOIN		stmt = select(User, Item).outerjoin(Item)	db.execute(stmt).all() (튜플 리스트)
COUNT All	SELECT count(*) FROM users;	stmt = select(func.count()).select_from(User)	db.scalar(stmt) (정수 값)
COUNT Filter	SELECT count(*) FROM users WHERE name = 'Alice';	stmt = select(func.count()).where(User.name == 'Alice')	db.scalar(stmt) (정수 값)