参考这篇文档
https://eco.dameng.com/docs/zh-cn/app-dev/python-SQLAlchemy.html

可以参考下：
注意需要用2.0版本的sqlalchemy

from flask import Flask, Response, json
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)

# 设置数据库链接地址
app.config['SQLALCHEMY_DATABASE_URI'] = 'dm+dmPython://SYSDBA:SYSDBA@192.168.186.3:5239'
# 设置显示底层执行的sql语句
app.config['SQLALCHEMY_ECHO'] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] =True

# 初始化组件对象，关联flask应用
db = SQLAlchemy(app)


# 构建模型类
class Buscar(db.Model):
    # 设置表名，表名默认为类名小写
    __tablename__ = 'bus_car'
    carnumber = db.Column(db.String(255), primary_key=True)
    cartype = db.Column(db.String(255))
    color = db.Column(db.String(255))
    price = db.Column(db.Numeric(19, 4))
    rentprice = db.Column(db.Numeric(19, 4))
    deposit = db.Column(db.Numeric(19, 4))
    isrenting = db.Column(db.Integer)
    description = db.Column(db.String(255))
    carimg = db.Column(db.String(255))
    createtime = db.Column(db.Date)

    def __repr__(self):  # 自定义 交互模式 & print() 的对象打印
        return "(%s, %s)" % (self.carnumber, self.cartype)


@app.route("/query")
def query():
    # 查询所有用户数据, 返回User列表,
    data = Buscar.query.all()
    response_list = dict()
    for item in data:
        response_list['carnumber']=item.carnumber
        response_list['cartype'] =item.cartype

    return Response(json.dumps(response_list), mimetype='application/json')


if __name__ == '__main__':
    app.run(host="192.168.186.3", port=5888, debug=True)