通过用户模型，对数据库进行增删改查操作。

增加：
user = 
db.session.add(user)
db.session.commit()

查询：
User.query.filter(User.username == 'mis1114').first()

修改：
user.password = '111111'
db.session.commit()

删除：
db.session.delete(user)
db.session.commit()

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
import config

app = Flask(__name__)
app.config.from_object(config)

db=SQLAlchemy(app)

class User(db.Model):
    __tablename__ = 'User'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    username = db.Column(db.String(20),nullable=False)
    password = db.Column(db.String(20), nullable=False)
    nickname = db.Column(db.String(20), nullable=True)

#db.create_all()
#增加
user=User(username='liuda',password='123456')
db.session.add(user)
db.session.commit()

#查询记录
user=User.query.filter(User.username=='liuda').first()
print(user.id,user.password)

#修改记录
user.password='1996'
db.session.commit()

#删除记录
db.session.delete(user)
db.session.commit()

@app.route('/')
def hello_world():
    return 'Hello World!'

if __name__ == '__main__':
    app.run()

SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://root:@localhost:3306/mis?charset=utf8'
SQLALCHEMY_TRACK_MODIFICATIONS = False