如何使左外连接与flask-sqlalchemy和解决我的情况?

Question

有三个表:

class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
score = db.Column(db.Integer, nullable=False, default=0)
results = db.relationship('Result', backref='solver', lazy='dynamic')
class Riddle(db.Model):
id = db.Column(db.Integer, primary_key=True)
text = db.Column(db.String, unique=True, nullable=False)
answer = db.Column(db.String, nullable=False)
solutions = db.relationship('Result', backref='rebus', lazy='dynamic')
points = db.Column(db.Integer, default=1)
class Result(db.Model):
id = db.Column(db.Integer, primary_key=True) 
user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
riddle_id = db.Column(db.Integer, db.ForeignKey('riddle.id'))
is_completed = db.Column(db.Boolean, nullable=False, default=False)

如何加入"谜语"?和";result"表，并获得所有字段在第一个不是在用户的结果?

简单地说，我需要在结果表中获得所有带有谜语的字段，这些字段的id用户没有。

Answer 1

答案找到了:

SQL:

SELECT *
FROM riddle
EXCEPT
SELECT riddle.*
FROM riddle
JOIN result ON result.riddle_id = riddle.id
WHERE result.user_id = 1

PYTHON:

riddle = Riddle.query.filter(Riddle.theme == theme_id) 
.except_(Riddle.query.join(Result, Result.riddle_id == Riddle.id) 
.filter(Result.user_id == user.id)).all()