时间:2021-07-01 10:21:17 帮助过:9人阅读
- <code>from flask import Flask
- from flask_sqlalchemy import SQLAlchemy
- app = Flask(__name__)
- db = SQLAlchemy(app)
- app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://root:root@localhost/flask'</code>
- <code>class Singer(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(70), unique=True)
- songs = db.relationship('Song', backref='singer')
- class Song(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(70), unique=True)
- singer_id = db.Column(db.Integer, db.ForeignKey('singer.id'))</code>
比一对多的用法,会少一个从一里访问多的字段。
- <code>class Citizen(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(70), unique=True)
- city_id = db.Column(db.Integer, db.ForeignKey('city.id'))
- city = db.relationship('City')
- class Country(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(79), unique=True)
- capital = db.relationship('Capital', uselist=False)</code>
- <code>class Country(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(79), unique=True)
- capital = db.relationship('Capital', uselist=False)
- class Capital(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(70), unique=True)
- country_id = db.Column(db.Integer, db.ForeignKey('country.id'))
- country = db.relationship('Country'</code>
- <code>association_table = db.Table(
- 'association',
- db.Column('student_id', db.Integer, db.ForeignKey('student.id')),
- db.Column('teacher_id', db.Integer, db.ForeignKey('teacher.id'))
- )
- class Student(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(70), unique=True)
- grade = db.Column(db.String(20))
- teachers = db.relationship(
- 'Teacher', secondary=association_table, backref='students')
- class Teacher(db.Model):
- id = db.Column(db.Integer, primary_key=True)
- name = db.Column(db.String(70), unique=True)
- office = db.Column(db.String(20))</code>
Flask数据库关系
标签:int key foreign iat table ons ati back teacher