伸缩自如的Flask [day12] Sql Database

好的，这里来使用Sql的DataBase，我相信你已经知道或调查过了NoSql跟Sql两种Database之间的差异。
至于为甚么NoSql常用于大数据?从大大的口中得知了，你可以将一些计算量庞大的统计值，使用key-value的型态存起来然后定期更改value，这样可以节省庞大的计算量。

再来安装mySql的地点:
https://dev.mysql.com/downloads/mysql/

以及使用python来操作mySql套件的介绍flask-sqlalchemy:
https://flask-sqlalchemy.palletsprojects.com/en/2.x/quickstart/

pip install flask-sqlalchemy

建立连线yourapplication.py档以及table中物件:

from flask import Flaskfrom flask_sqlalchemy import SQLAlchemyapp = Flask(__name__)app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'db = SQLAlchemy(app)class User(db.Model):    id = db.Column(db.Integer, primary_key=True)    username = db.Column(db.String(80), unique=True, nullable=False)    email = db.Column(db.String(120), unique=True, nullable=False)    def __repr__(self):        return '<User %r>' % self.username

使用之前，先在cmd打入下列指令以在DB中建立table中物件:

>>> from yourapplication import db>>> db.create_all()

写入资料:

from yourapplication import User,dbadmin = User(username='admin', email='admin@example.com')guest = User(username='guest', email='guest@example.com')db.session.add(admin)db.session.add(guest)db.session.commit()

删除资料:

me = User('admin', 'admin@example.com')db.session.delete(me)db.session.commit()

搜索资料:

peter = User.query.filter_by(username='peter').first()print(peter.id)

[day 1] 开场白[day 2] blue_print[day 3] Factory mode[day 4] JWT token[day 5] session[day 6] Jinja[day 7] Post data with Form tag[day 8] ajax with jquery[day 9] request[day 10] 将资料写进DB(pymongo)[day 11] log with mongoDB[day 12] Sql Database[day 13] 档案上传[day 14] 档案下载 及 其他传值方法[day 15] boostrap 4.6[day 16] API[day 17] Docker image化--安装篇[day 18] Docker image化--运行篇[day 19] Nginx[day 20] Docker compose[day 21] Nginx with https[day 22] pythonanywhere 部署[day 23] GCP app engine (介绍)[day 24] GCP app engine (deploy)[day 25] Flask with web cam[day 26] Flask with ML[day 27] Supervisor[day 28] Flask-Mail[day 29] Line Messaging API[day 30] 结语