目录
wtforms
安装：pip3 install wtforms
使用1：
from flask import Flask, render_template, request, redirect
from wtforms import Form
from wtforms.fields import simple
from wtforms import validators
from wtforms import widgets
app = Flask(__name__, template_folder='templates')
app.debug = True
class LoginForm(Form):
# 字段（内部包含正则表达式）
name = simple.StringField(
label='用户名',
validators=[
validators.DataRequired(message='用户名不能为空.'),
validators.Length(min=6, max=18, message='用户名长度必须大于%(min)d且小于%(max)d')
],
widget=widgets.TextInput(), # 页面上显示的插件
render_kw={'class': 'form-control'}
)
# 字段（内部包含正则表达式）
pwd = simple.PasswordField(
label='密码',
validators=[
validators.DataRequired(message='密码不能为空.'),
validators.Length(min=8, message='用户名长度必须大于%(min)d'),
validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*d)(?=.*[$@$!%*?&])[A-Za-zd$@$!%*?&]{8,}",
message='密码至少8个字符，至少1个大写字母，1个小写字母，1个数字和1个特殊字符')
],
widget=widgets.PasswordInput(),
render_kw={'class': 'form-control'}
)
@app.route('/login', methods=['GET', 'POST'])
def login():
if request.method == 'GET':
form = LoginForm()
return render_template('login.html', form=form)
else:
form = LoginForm(formdata=request.form)
if form.validate():
print('用户提交数据通过格式验证，提交的值为：', form.data)
else:
print(form.errors)
return render_template('login.html', form=form)
if __name__ == '__main__':
app.run()
login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>登录</h1>
<form method="post">
<p>{{form.name.label}} {{form.name}} {{form.name.errors[0] }}</p>
<p>{{form.pwd.label}} {{form.pwd}} {{form.pwd.errors[0] }}</p>
<input type="submit" value="提交">
</form>
</body>
</html>
使用2：
from flask import Flask, render_template, request, redirect
from wtforms import Form
from wtforms.fields import core
from wtforms.fields import html5
from wtforms.fields import simple
from wtforms import validators
from wtforms import widgets
app = Flask(__name__, template_folder='templates')
app.debug = True
class RegisterForm(Form):
name = simple.StringField(
label='用户名',
validators=[
validators.DataRequired()
],
widget=widgets.TextInput(),
render_kw={'class': 'form-control'},
default='cxw'
)
pwd = simple.PasswordField(
label='密码',
validators=[
validators.DataRequired(message='密码不能为空.')
],
widget=widgets.PasswordInput(),
render_kw={'class': 'form-control'}
)
pwd_confirm = simple.PasswordField(
label='重复密码',
validators=[
validators.DataRequired(message='重复密码不能为空.'),
validators.EqualTo('pwd', message="两次密码输入不一致")
],
widget=widgets.PasswordInput(),
render_kw={'class': 'form-control'}
)
email = html5.EmailField(
label='邮箱',
validators=[
validators.DataRequired(message='邮箱不能为空.'),
validators.Email(message='邮箱格式错误')
],
widget=widgets.TextInput(input_type='email'),
render_kw={'class': 'form-control'}
)
gender = core.RadioField(
label='性别',
choices=(
(1, '男'),
(2, '女'),
),
#这句话的意思是上面的choices元组的第一个值是int类型
#如果上上面为(‘1’, '男'),(‘2’, '女'),则下面的coerce则不用写
coerce=int # “1” “2”
)
#这里是单选框
city = core.SelectField(
label='城市',
choices=(
('bj', '北京'),
('sh', '上海'),
)
)
#这里是多选框
hobby = core.SelectMultipleField(
label='爱好',
choices=(
(1, '篮球'),
(2, '足球'),
),
coerce=int
)
#这里是多选的checkbox
favor = core.SelectMultipleField(
label='喜好',
choices=(
(1, '篮球'),
(2, '足球'),
),
widget=widgets.ListWidget(prefix_label=False),
option_widget=widgets.CheckboxInput(),
coerce=int,
default=[1, 2]
)
#这里可以改值
def __init__(self, *args, **kwargs):
super(RegisterForm, self).__init__(*args, **kwargs)
self.favor.choices = ((1, '篮球'), (2, '足球'), (3, '羽毛球'))
def validate_pwd_confirm(self, field):
"""
自定义pwd_confirm字段规则，例：与pwd字段是否一致
:param field:
:return:
"""
# 最开始初始化时，self.data中已经有所有的值
if field.data != self.data['pwd']:
# raise validators.ValidationError("密码不一致") # 继续后续验证
raise validators.StopValidation("密码不一致") # 不再继续后续验证
@app.route('/register', methods=['GET', 'POST'])
def register():
if request.method == 'GET':
#这里可以传默认值
form = RegisterForm(data={'gender': 2,'hobby':[1,]}) # initial
return render_template('register.html', form=form)
else:
form = RegisterForm(formdata=request.form)
if form.validate():
print('用户提交数据通过格式验证，提交的值为：', form.data)
else:
print(form.errors)
return render_template('register.html', form=form)
if __name__ == '__main__':
app.run()
register.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>用户注册</h1>
<form method="post" novalidate style="padding:0 50px">
{% for field in form %}
<p>{{field.label}}: {{field}} {{field.errors[0] }}</p>
{% endfor %}
<input type="submit" value="提交">
</form>
</body>
</html>
多app应用
from werkzeug.wsgi import DispatcherMiddleware
from werkzeug.serving import run_simple
from flask import Flask, current_app
app1 = Flask('app01')
app2 = Flask('app02')
@app1.route('/index')
def index():
return "app01"
@app2.route('/index2')
def index2():
return "app2"
# localhost:5000/index
# localhost:5000/sec/index2
dm = DispatcherMiddleware(app1, {
'/sec': app2,
})
if __name__ == "__main__":
run_simple('localhost', 5000, dm)
flask-script
用于实现类似于django中 python3 manage.py runserver ...类似的命令
安装：pip3 install flask-script
使用：
from flask import Flask,request
from flask_script import Manager
app = Flask(__name__)
manager=Manager(app)
@app.route("/")
def index():
return "ok"
if __name__ == '__main__':
manager.run()
#以后在执行，直接：python3 manage.py runserver
#python3 manage.py runserver --help
自定义命令：
from flask import Flask
from flask_script import Manager
app = Flask(__name__)
manager=Manager(app)
@app.route("/")
def index():
return "ok"
@manager.command
def custom(arg):
"""
自定义命令
python manage.py custom 123
:param arg:
:return:
"""
print(arg)
@manager.option('-n', '--name', dest='name')
@manager.option('-u', '--url', dest='url')
def cmd(name, url):
"""
自定义命令（-n也可以写成--name）
执行： python manage.py cmd -n lqz -u http://www.oldboyedu.com
执行： python manage.py cmd --name lqz --url http://www.oldboyedu.com
:param name:
:param url:
:return:
"""
print(name, url)
#有什么用？
#把excel的数据导入数据库，定制个命令，去执行
if __name__ == '__main__':
manager.run()
SQLAlchemy
SQLAlchemy是一个基于Python实现的ORM框架。该框架建立在 DB API之上，使用关系对象映射进行数据库操作，简言之便是：将类和对象转换成SQL，然后使用数据API执行SQL并获取执行结果。
pip3 install sqlalchemy
组成部分：
Engine，框架的引擎
Connection Pooling ，数据库连接池
Dialect，选择连接数据库的DB API种类
Schema/Types，架构和类型
SQL Exprression Language，SQL表达式语言
SQLAlchemy本身无法操作数据库，其必须以来pymsql等第三方插件，Dialect用于和数据API进行交流，根据配置文件的不同调用不同的数据库API，从而实现对数据库的操作，如：
MySQL-Python
mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>
pymysql
mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]
MySQL-Connector
mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>
cx_Oracle
oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]
更多：http://docs.sqlalchemy.org/en/latest/dialects/index.html
django中如何反向生成models
python manage.py inspectdb > app/models.py
简单使用（能创建表，删除表，不能修改表）
修改表：在数据库添加字段，类对应上
1执行原生sql（不常用）
import time
import threading
import sqlalchemy
from sqlalchemy import create_engine
from sqlalchemy.engine.base import Engine
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/test?charset=utf8",
max_overflow=0, # 超过连接池大小外最多创建的连接
pool_size=5, # 连接池大小
pool_timeout=30, # 池中没有线程最多等待的时间，否则报错
pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收（重置）
)
def task(arg):
conn = engine.raw_connection()
cursor = conn.cursor()
cursor.execute(
"select * from app01_book"
)
result = cursor.fetchall()
print(result)
cursor.close()
conn.close()
for i in range(20):
t = threading.Thread(target=task, args=(i,))
t.start()
2 orm使用
import datetime
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index
Base = declarative_base()
class Users(Base):
__tablename__ = 'users' # 数据库表名称
id = Column(Integer, primary_key=True) # id 主键
name = Column(String(32), index=True, nullable=False) # name列，索引，不可为空
# email = Column(String(32), unique=True)
#datetime.datetime.now不能加括号，加了括号，以后永远是当前时间
# ctime = Column(DateTime, default=datetime.datetime.now)
# extra = Column(Text, nullable=True)
__table_args__ = (
# UniqueConstraint('id', 'name', name='uix_id_name'), #联合唯一
# Index('ix_id_name', 'name', 'email'), #索引
)
def init_db():
"""
根据类创建数据库表
:return:
"""
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/aaa?charset=utf8",
max_overflow=0, # 超过连接池大小外最多创建的连接
pool_size=5, # 连接池大小
pool_timeout=30, # 池中没有线程最多等待的时间，否则报错
pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收（重置）
)
Base.metadata.create_all(engine)
def drop_db():
"""
根据类删除数据库表
:return:
"""
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/aaa?charset=utf8",
max_overflow=0, # 超过连接池大小外最多创建的连接
pool_size=5, # 连接池大小
pool_timeout=30, # 池中没有线程最多等待的时间，否则报错
pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收（重置）
)
Base.metadata.drop_all(engine)
if __name__ == '__main__':
# drop_db()
init_db()
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Users
#"mysql+pymysql://root@127.0.0.1:3306/aaa"
engine = create_engine("mysql+pymysql://root:123456@127.0.0.1:3306/aaa", max_overflow=0, pool_size=5)
Connection = sessionmaker(bind=engine)
# 每次执行数据库操作时，都需要创建一个Connection
con = Connection()
# ############# 执行ORM操作 #############
obj1 = Users(name="lqz")
con.add(obj1)
# 提交事务
con.commit()
# 关闭session，其实是将连接放回连接池
con.close()
一对多关系
class Hobby(Base):
__tablename__ = 'hobby'
id = Column(Integer, primary_key=True)
caption = Column(String(50), default='篮球')
class Person(Base):
__tablename__ = 'person'
nid = Column(Integer, primary_key=True)
name = Column(String(32), index=True, nullable=True)
# hobby指的是tablename而不是类名，uselist=False
hobby_id = Column(Integer, ForeignKey("hobby.id"))
# 跟数据库无关，不会新增字段，只用于快速链表操作
# 类名，backref用于反向查询
hobby=relationship('Hobby',backref='pers')
多对多关系
class Boy2Girl(Base):
__tablename__ = 'boy2girl'
id = Column(Integer, primary_key=True, autoincrement=True)
girl_id = Column(Integer, ForeignKey('girl.id'))
boy_id = Column(Integer, ForeignKey('boy.id'))
class Girl(Base):
__tablename__ = 'girl'
id = Column(Integer, primary_key=True)
name = Column(String(64), unique=True, nullable=False)
class Boy(Base):
__tablename__ = 'boy'
id = Column(Integer, primary_key=True, autoincrement=True)
name = Column(String(64), unique=True, nullable=False)
# 与生成表结构无关，仅用于查询方便,放在哪个单表中都可以
girl = relationship('Girl', secondary='boy2girl', backref='boys')
操作数据表
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Users
engine = create_engine("mysql+pymysql://root:123456@127.0.0.1:3306/aaa", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
# 每次执行数据库操作时，都需要创建一个session
session = Session()
# ############# 执行ORM操作 #############
obj1 = Users(name="lqz")
session.add(obj1)
# 提交事务
session.commit()
# 关闭session
session.close()
基于scoped_session实现线程安全
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session
from models import Users
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
"""
# 线程安全，基于本地线程实现每个线程用同一个session
# 特殊的：scoped_session中有原来方法的Session中的一下方法：
public_methods = (
'__contains__', '__iter__', 'add', 'add_all', 'begin', 'begin_nested',
'close', 'commit', 'connection', 'delete', 'execute', 'expire',
'expire_all', 'expunge', 'expunge_all', 'flush', 'get_bind',
'is_modified', 'bulk_save_objects', 'bulk_insert_mappings',
'bulk_update_mappings',
'merge', 'query', 'refresh', 'rollback',
'scalar'
)
"""
#scoped_session类并没有继承Session,但是却又它的所有方法
session = scoped_session(Session)
# ############# 执行ORM操作 #############
obj1 = Users(name="alex1")
session.add(obj1)
# 提交事务
session.commit()
# 关闭session
session.close()
基本增删查改
import time
import threading
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import create_engine
from sqlalchemy.sql import text
from db import Users, Hosts
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session = Session()
# ################ 添加 ################
"""
obj1 = Users(name="wupeiqi")
session.add(obj1)
session.add_all([
Users(name="lqz"),
Users(name="egon"),
Hosts(name="c1.com"),
])
session.commit()
"""
# ################ 删除 ################
"""
session.query(Users).filter(Users.id > 2).delete()
session.commit()
"""
# ################ 修改 ################
"""
#传字典
session.query(Users).filter(Users.id > 0).update({"name" : "lqz"})
#类似于django的F查询，这个后面必须配合synchronize_session，
#如果是字符串就用False，如果是数字就用#evaluata
session.query(Users).filter(Users.id > 0).update({Users.name: Users.name + "099"}, synchronize_session=False)
session.query(Users).filter(Users.id > 0).update({"age": Users.age + 1}, synchronize_session="evaluate")
session.commit()
"""
# ################ 查询 ################
"""
r1 = session.query(Users).all()
#只取age列，把name重命名为xx
r2 = session.query(Users.name.label('xx'), Users.age).all()
#filter传的是表达式，filter_by传的是参数
r3 = session.query(Users).filter(Users.name == "lqz").all()
r4 = session.query(Users).filter_by(name='lqz').all()
r5 = session.query(Users).filter_by(name='lqz').first()
#:value 和:name 相当于占位符，用params传参数
r6 = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name='fred').order_by(Users.id).all()
#自定义查询sql
r7 = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name='ed').all()
"""
#增，删，改都要commit()
session.close()
常用操作
# 条件
ret = session.query(Users).filter_by(name='lqz').all()
#表达式，and条件连接
ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()
ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()
#注意下划线
ret = session.query(Users).filter(Users.id.in_([1,3,4])).all()
#~非，除。。外
ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()
#二次筛选
ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all()
from sqlalchemy import and_, or_
#or_包裹的都是or条件，and_包裹的都是and条件
ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()
ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()
ret = session.query(Users).filter(
or_(
Users.id < 2,
and_(Users.name == 'eric', Users.id > 3),
Users.extra != ""
)).all()
# 通配符，以e开头，不以e开头
ret = session.query(Users).filter(Users.name.like('e%')).all()
ret = session.query(Users).filter(~Users.name.like('e%')).all()
# 限制，用于分页，区间
ret = session.query(Users)[1:2]
# 排序，根据name降序排列（从大到小）
ret = session.query(Users).order_by(Users.name.desc()).all()
#第一个条件重复后，再按第二个条件升序排
ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all()
# 分组
from sqlalchemy.sql import func
ret = session.query(Users).group_by(Users.extra).all()
#分组之后取最大id，id之和，最小id
ret = session.query(
func.max(Users.id),
func.sum(Users.id),
func.min(Users.id)).group_by(Users.name).all()
#haviing筛选
ret = session.query(
func.max(Users.id),
func.sum(Users.id),
func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()
# 连表（默认用forinkey关联）
ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all()
#join表，默认是inner join
ret = session.query(Person).join(Favor).all()
#isouter=True 外连，表示Person left join Favor，没有右连接，反过来即可
ret = session.query(Person).join(Favor, isouter=True).all()
#打印原生sql
aa=session.query(Person).join(Favor, isouter=True)
print(aa)
# 自己指定on条件（连表条件）,第二个参数，支持on多个条件，用and_,同上
ret = session.query(Person).join(Favor,Person.id==Favor.id, isouter=True).all()
# 组合（了解）UNION 操作符用于合并两个或多个 SELECT 语句的结果集
#union和union all的区别？
q1 = session.query(Users.name).filter(Users.id > 2)
q2 = session.query(Favor.caption).filter(Favor.nid < 2)
ret = q1.union(q2).all()
q1 = session.query(Users.name).filter(Users.id > 2)
q2 = session.query(Favor.caption).filter(Favor.nid < 2)
ret = q1.union_all(q2).all()
执行原生sql
import time
import threading
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import create_engine
from sqlalchemy.sql import text
from sqlalchemy.engine.result import ResultProxy
from db import Users, Hosts
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session = Session()
# 查询
# cursor = session.execute('select * from users')
# result = cursor.fetchall()
# 添加
cursor = session.execute('insert into users(name) values(:value)',params={"value":'lqz'})
session.commit()
print(cursor.lastrowid)
session.close()
一对多
import time
import threading
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import create_engine
from sqlalchemy.sql import text
from sqlalchemy.engine.result import ResultProxy
from db import Users, Hosts, Hobby, Person
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session = Session()
# 添加
"""
session.add_all([
Hobby(caption='乒乓球'),
Hobby(caption='羽毛球'),
Person(name='张三', hobby_id=3),
Person(name='李四', hobby_id=4),
])
person = Person(name='张九', hobby=Hobby(caption='姑娘'))
session.add(person)
#添加二
hb = Hobby(caption='人妖')
hb.pers = [Person(name='文飞'), Person(name='博雅')]
session.add(hb)
session.commit()
"""
# 使用relationship正向查询
"""
v = session.query(Person).first()
print(v.name)
print(v.hobby.caption)
"""
# 使用relationship反向查询
"""
v = session.query(Hobby).first()
print(v.caption)
print(v.pers)
"""
#方式一，自己链表
# person_list=session.query(models.Person.name,models.Hobby.caption).join(models.Hobby,isouter=True).all()
person_list=session.query(models.Person,models.Hobby).join(models.Hobby,isouter=True).all()
for row in person_list:
# print(row.name,row.caption)
print(row[0].name,row[1].caption)
#方式二：通过relationship
person_list=session.query(models.Person).all()
for row in person_list:
print(row.name,row.hobby.caption)
#查询喜欢姑娘的所有人
obj=session.query(models.Hobby).filter(models.Hobby.id==1).first()
persons=obj.pers
print(persons)
session.close()
多对多
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sql.models import Girl,Boy,Boy2Girl
engine = create_engine("mysql+pymysql://root:@127.0.0.1:3307/flask-test?charset=utf8", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session = Session()
# 添加
'''
session.add_all([
Girl(name='g_com1'),
Girl(name='g2.com1'),
Boy(name='A组1'),
Boy(name='B组2'),
])
session.commit()
s2g = Boy2Girl(girl_id=2, boy_id =2)
session.add(s2g)
session.commit()
gp = Boy(name='C组')
gp.girl = [Girl(name='c3.com'),Girl(name='c4.com')]
session.add(gp)
session.commit()
ser = Girl(name='c6.com')
ser.boys = [Boy(name='F组pp'),Boy(name='G组ll')]
session.add(ser)
session.commit()
'''
"""
# 使用relationship正向查询
"""
'''
v = session.query(Boy).first()
print(v.name)
print(v.girl)
'''
# 使用relationship反向查询
'''
v = session.query(Girl).first()
print(v.name)
print(v.boys)
'''
session.close()
其它
import time
import threading
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import create_engine
from sqlalchemy.sql import text, func
from sqlalchemy.engine.result import ResultProxy
from db import Users, Hosts, Hobby, Person, Group, Server, Server2Group
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)
session = Session()
# 关联子查询:correlate(Group)表示跟Group表做关联，as_scalar相当于对该sql加括号，用于放在后面当子查询
subqry = session.query(func.count(Server.id).label("sid")).filter(Server.id == Group.id).correlate(Group).as_scalar()
result = session.query(Group.name, subqry)
"""
SELECT `group`.name AS group_name, (SELECT count(server.id) AS sid
FROM server
WHERE server.id = `group`.id) AS anon_1
FROM `group`
"""
'''
select * from tb where id in [select id from xxx];
select id,
name,
#必须保证此次查询只有一个值
(select max(id) from xxx) as mid
from tb
例如，第三个字段只能有一个值
id name mid
1 lqz 1，2 不合理
2 egon 2
'''
'''
成绩表：
id sid cid score
1 1 物理 99
2 1 化学 88
3 2 物理 95
学生表：
id name 每个学生总分数
1 xx 88
2 yy 77
select id，name,
(select avr(score) from 成绩表 where 成绩表.sid=学生表.id) as x
from 学生表
subqry = session.query(func.count(成绩表.scort).label("sc")).filter(学生表.id == 成绩表.sid).correlate(学生表).as_scalar()
result = session.query(学生表.name, subqry)
'''
# 原生SQL
"""
# 查询
cursor = session.execute('select * from users')
result = cursor.fetchall()
# 添加
cursor = session.execute('insert into users(name) values(:value)',params={"value":'wupeiqi'})
session.commit()
print(cursor.lastrowid)
"""
session.close()
Flask-SQLAlchemy
lask和SQLAchemy的管理者，通过他把他们做连接
db = SQLAlchemy()
- 包含配置
- 包含ORM基类
- 包含create_all
- engine
- 创建连接
flask-migrate
python3 manage.py db init 初始化：只执行一次
python3 manage.py db migrate 等同于 makemigartions
python3 manage.py db upgrade 等同于migrate