[英]How to make left outer join with flask-sqlalchemy and solve my case?
共有三张表:
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“结果”表并获取第一个不在用户结果中的所有字段?
简单地说,我需要获取用户在结果表中没有其 ID 的所有带有谜语的字段。
找到了答案:
查询语句:
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()
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