由於 MySQL-python 不支援 Python 3（MySQL-3.23 through 5.5 and Python-2.4 through 2.7 are currently supported），python3下使用flask-sqlalchemy時，安裝的命令是：

pip install pymysql
pip install flask-sqlalchemy

  相關程式碼如下：

# config.py

SECRET_KEY = 'flaskMysql'
SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://user:[email protected]
 
:port/dbname'
SQLALCHEMY_TRACK_MODIFICATIONS = True
DEBUG = True 

# _init_.py

from flask import Flask, render_template, jsonify
from db_mysql import db

app = Flask(__name__) # 新建app物件
app.config.from_object('config') # 載入配置資訊，其中有資料庫的配置資訊，包含在SQLALCHEMY_DATABASE_URI中


# 初始化db,並建立models中定義的表格
with app.app_context(): # 新增這一句，否則會報資料庫找不到application和context錯誤
    db.init_app(app) # 初始化db
    db.create_all() # 建立所有未建立的table
 

#db_mysql.py

from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, nullable=False, primary_key=True, autoincrement=True)
    username = db.Column(db.String(32), nullable=False, unique=True, server_default='', index=True)
    role_id = db.Column(db.Integer, nullable=False, server_default='0')

    def __init__(self,username,role_id):
        self.username = username
        self.role_id = role_id

    def __repr__(self):
        return '<User %r,Role id %r>' %(self.username,self.role_id)

class Role(db.Model):
    __tablename__ = 'roles'
    id = db.Column(db.Integer, nullable=False, primary_key=True, autoincrement=True)
    name = db.Column(db.String(16), nullable=False, server_default='', unique=True)

    def __init__(self,name):
        self.name = name

    def __repr__(self):
        return '<Role %r>' % self.name

 

資料庫關聯操作：

#按使用者名稱摸糊查詢
User.query.join(Role).filter(Users.username.like('%xx%'))
#select xxx from User inner join Role on user.role_id=role.id where user.username like '%xx%'

#左外聯接(left join)
User.query.outerjoin(Role).filter(Users.username.like('%xx%'))
#select xxx from User left outer join Role on user.role_id=role.id where user.username like '%xx%'

#以上是已經設定好外來鍵,它自動找到關聯的欄位.也可以自己指定:
User.query.join(Role,User.role_id==Role.id).filter(User.username.like('%xx%'))
#select xxx from User inner join User on user.role_id=role.id where user.username like '%xx%'