Flask数据库关系

概述基础配置 from flask import Flaskfrom flask_sqlalchemy import SQLAlchemyapp = Flask(__name__)db = SQLAlchemy(app)app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://root:[email protected]/flask' 基础配置

from flask import Flaskfrom flask_sqlalchemy import sqlAlchemyapp = Flask(__name__)db = sqlAlchemy(app)app.config['sqlALCHEMY_DATABASE_URI'] = 'MysqL+pyMysqL://root:[email protected]/flask'

一对多

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,unique=True)    singer_ID = db.Column(db.Integer,db.ForeignKey('singer.ID'))

多对一（不是必须时还是用与一对多吧）

比一对多的用法，会少一个从一里访问多的字段。

class CitiZen(db.Model):    ID = db.Column(db.Integer,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)

一对一

class Country(db.Model):    ID = db.Column(db.Integer,useList=False)class CAPItal(db.Model):    ID = db.Column(db.Integer,unique=True)    country_ID = db.Column(db.Integer,db.ForeignKey('country.ID'))    country = db.relationship('Country'

多对多

association_table = db.table(    'association',db.Column('student_ID',db.Integer,db.ForeignKey('student.ID')),db.Column('teacher_ID',db.ForeignKey('teacher.ID')))class Student(db.Model):    ID = db.Column(db.Integer,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,unique=True)    office = db.Column(db.String(20))

总结

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