1、pycharm中新建一个flask项目

2、按装flask、PyMySQL、flask-sqlalchemy

3、项目下面新建一个config.py 文件

DEBUG = True
#dialect+driver://root:1q2w3e4r5t@127.0.0.1:3306/
DIALECT = 'mysql'
DRIVER='pymysql'
USERNAME = 'root'
PASSWORD = '1q2w3e4r5t'
HOST = '127.0.0.1'
PORT = 3306
DATABASE = 'db_demo1'

SQLALCHEMY_DATABASE_URI = "{}+{}://{}:{}@{}:{}/{}?charset=utf8".format(DIALECT,DRIVER,USERNAME,PASSWORD,HOST,PORT,DATABASE)
SQLALCHEMY_TRACK_MODIFICATIONS = False
print(SQLALCHEMY_DATABASE_URI)

4、app.py 文件

from flask import Flask
import config

from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config.from_object(config)

db = SQLAlchemy(app)
db.create_all()



@app.route('/')
def index():
    return 'index'



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

执行app.py 文件，结果如下，表面执行成功

from flask import Flask
import config

from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config.from_object(config)

db = SQLAlchemy(app)
db.create_all()



@app.route('/')
def index():
    return 'index'



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

FLASK_APP = test_sqlalchemy.py
FLASK_ENV = development
FLASK_DEBUG = 1
In folder /Users/autotest/PycharmProjects/python3_flask
/Users/autotest/PycharmProjects/python3_flask/venv/bin/python /Applications/PyCharm.app/Contents/helpers/pydev/pydevd.py --module --multiproc --qt-support=auto --client 127.0.0.1 --port 55365 --file flask run
pydev debugger: process 3089 is connecting

Connected to pydev debugger (build 182.4505.26)
* Serving Flask app "test_sqlalchemy.py" (lazy loading)
* Environment: development
* Debug mode: on
mysql+pymysql://root:1q2w3e4r5t@127.0.0.1:3306/db_demo1?charset=utf8
* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
* Restarting with stat
pydev debugger: process 3090 is connecting

mysql+pymysql://root:1q2w3e4r5t@127.0.0.1:3306/db_demo1?charset=utf8
* Debugger is active!
* Debugger PIN: 216-502-598

往数据库中添加一张保存文章的表，表明为article，字段有id，title，content

同样一个配置文件：config.py

DEBUG = True
#dialect+driver://root:1q2w3e4r5t@127.0.0.1:3306/
DIALECT = 'mysql'
DRIVER='pymysql'
USERNAME = 'root'
PASSWORD = '1q2w3e4r5t'
HOST = '127.0.0.1'
PORT = 3306
DATABASE = 'db_demo1'

SQLALCHEMY_DATABASE_URI = "{}+{}://{}:{}@{}:{}/{}?charset=utf8".format(DIALECT,DRIVER,USERNAME,PASSWORD,HOST,PORT,DATABASE)
SQLALCHEMY_TRACK_MODIFICATIONS = False
print(SQLALCHEMY_DATABASE_URI)

flask app 中新建一个class Blog，里面定义好id ，title ，content。代码执行到db.create_all()时，会自动在数据库中创建一个表，表明为blog

from flask import Flask
import config

from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.ext.declarative import declarative_base

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

db = SQLAlchemy(app)
Base = declarative_base()


class Blog(db.Model):
    __tablename__ = 'blog'
    id  = db.Column(db.Integer,primary_key=True,autoincrement=True)
    title = db.Column(db.String(100),nullable=False)
    content = db.Column(db.Text,nullable=True)


db.create_all()


@app.route('/')
def index():
    return 'index'


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

启动flask app，数据库中查询表和表结构如下，有新增相应的表，说明新建表成功

数据库表中的数据增删改查

    #新增
    blog = Blog(title="first blog",content="this is my first blog")
    db.session.add(blog)
    db.session.commit()

    #查询
    #res =Blog.query.filter(Blog.title=="first blog")[0]

    res =Blog.query.filter(Blog.title=="first blog").first()
    print(res.title)
     #修改
    blog_edit = Blog.query.filter(Blog.title=="first blog").first()
    blog_edit.title = "new first blog"
    db.session.commit()
    #删除
    blog_delete  = Blog.query.filter(Blog.title=="first blog").first()
    db.session.delete(blog_delete)
    db.session.commit()

完整代码

from flask import Flask
import config

from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.ext.declarative import declarative_base

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

db = SQLAlchemy(app)
Base = declarative_base()


class Blog(db.Model):
    __tablename__ = 'blog'
    id  = db.Column(db.Integer,primary_key=True,autoincrement=True)
    title = db.Column(db.String(100),nullable=False)
    content = db.Column(db.Text,nullable=True)


db.create_all()


@app.route('/')
def index():
    #新增
    blog = Blog(title="first blog",content="this is my first blog")
    db.session.add(blog)
    db.session.commit()

    #查询
    #res =Blog.query.filter(Blog.title=="first blog")[0]

    res =Blog.query.filter(Blog.title=="first blog").first()
    print(res.title)
     #修改
    blog_edit = Blog.query.filter(Blog.title=="first blog").first()
    blog_edit.title = "new first blog"
    db.session.commit()
    #删除
    blog_delete  = Blog.query.filter(Blog.title=="first blog").first()
    db.session.delete(blog_delete)
    db.session.commit()


    return 'index'


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