Flask基础学习2

连接mysql数据库测试(专业版)

[注意1：要导入text库，否则可能出现找不到select 1错误]

[注意2：若出现下列问题，可按照模板代码的顺序db = SQLAlchemy(app) 的位置]

RuntimeError: Either 'SQLALCHEMY_DATABASE_URI' or 'SQLALCHEMY_BINDS' must be set.

from flask_sqlalchemy import SQLAlchemy
from sqlalchemy import text
app = Flask(__name__)

# MySQL所在主机名，默认127.0.0.1
HOSTNAME = "127.0.0.1"
PORT = 3306
USERNAME = "root"
PASSWORD = "****"
DATABASE = "***"
app.config['SQLALCHEMY_DATABASE_URI'] = f"mysql+pymysql://{USERNAME}:{PASSWORD}@{HOSTNAME}:{PORT}/{DATABASE}?charset=utf8"

db = SQLAlchemy(app)

with app.app_context():
    with db.engine.connect() as conn:
        result = conn.execute(text("select 1"))
        print(result.fetchone())  # (1,)

ORM的实现

class User(db.Model):
    __tablename = 'admin'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    sname = db.Column(db.String(100),nullable=False)
    snumber = db.Column(db.String(100),nullable=False)
    address = db.Column(db.String(100),nullable=False)


with app.app_context():
    db.create_all()

命令行的实现及结果

mysql> show tables;
+---------------+
| Tables_in_flk |
+---------------+
| admin         |
| user          |
+---------------+
2 rows in set (0.00 sec)

mysql> desc admin;
+---------+--------------+------+-----+---------+----------------+
| Field   | Type         | Null | Key | Default | Extra          |
+---------+--------------+------+-----+---------+----------------+
| id      | int          | NO   | PRI | NULL    | auto_increment |
| sname   | varchar(100) | NO   |     | NULL    |                |
| snumber | varchar(100) | NO   |     | NULL    |                |
| address | varchar(100) | NO   |     | NULL    |                |
+---------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

 ORM插入实现

user = User(sname='pass', snumber=10, address='[email protected]')
db.session.add(user)
db.session.commit()

mysql> select * from admin;
+----+-------+---------+------------+
| id | sname | snumber | address    |
+----+-------+---------+------------+
|  1 | pass  | 10      | [email protected] |
+----+-------+---------+------------+
1 row in set (0.00 sec)

 ORM查询实现

user  = User.query.get(1)
print(user.sname)
# 输出 pass

ORM筛选实现

user  = User.query.filter_by(sname='pass')
print(user[0].address)
# 输出 [email protected]

ORM更新实现

user  = User.query.filter_by(sname='pass').first()
user.address = '[email protected]'
db.session.commit()

 ORM删除实现

user  = User.query.get(1)
db.session.delete(user)
db.session.commit()

其他待更新中。。。