标签：删除数据库 and 报错 filter str 记录 pytho 过滤 添加
models 文件
# pip install sqlalchemy
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
from sqlalchemy.orm import relationship
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
age = Column(Integer)
#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 __repr__(self):
return self.name
class Hobby(Base):
__tablename__ = "hobby"
id = Column(Integer,primary_key=True)
catption =Column(String(50),default="双色球")
class Person(Base):
__tablename__ = "person"
nid = Column(Integer,primary_key=True)
name = Column(String(32))
#hobby值tablename而不是Hobby类名，
hobby_id = Column(Integer,ForeignKey("hobby.id"))
# 更数据库没有关系，不会新增加字段，只能用于快速的链表查询操作
#relationship的第一个参数，是类名，第二个参数backref，用于反向查询
hobby =relationship("Hobby",backref="pres")
# 一个男孩可以喜欢多个女孩，一个女孩也可以喜欢多个男孩
class Boy2Girl(Base):
__tablename__ = "boy2girl"
id = Column(Integer, primary_key=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(100),nullable=False)
def __repr__(self):
return self.name
class Boy(Base):
__tablename__ = "boy"
id = Column(Integer, primary_key=True)
name = Column(String(100), nullable=False)
#secondary=boy2girl 中间表的表名
def init_db():
"""
根据类创建数据库表
:return:
"""
engine = create_engine(
"mysql+pymysql://root:@127.0.0.1:3307/python13?charset=utf8",
#"什么数据库（mysql,orcal）+用什么取链接数据库（pymysql）://数据库用户名:密码@mysqlip:端口/数据库名？charset=字符集"
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:@127.0.0.1:3307/python13?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()orm.py
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:@127.0.0.1:3307/python13", 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()
# 1 单增
# obj1 = Users(name="lsb1",age=12)
# con.add(obj1)
# 2 多个增加
# con.add_all([
# Users(name="lsb1",age=12),
# Users(name="esb",age=40),
# Users(name="jsb",age=30),
# Users(name="tsb",age=12),
# #Host(name = "tsb",time=123213)
# ])
# 3 删除
# con.query(Users).delete()
#4 改
# con.query(Users).update({"name":"sb","age":14})
# con.query(Users).update({Users.name:Users.name +" is true","age":1},synchronize_session=False)
# con.query(Users).update({Users.age:Users.age + 10})
# 5查(查是不需要commit,也能拿到结果)
#打印sql
# r1 = con.query(Users)
#查询所有
# r1 = con.query(Users).all()
#
#查单条记录
# r1 = con.query(Users).first()
#查哪些字段
# r1 = con.query(Users.age,Users.name.label("sb")).first()
#过滤用filter_by(传参数)或者filter（传表达式）
# r1 = con.query(Users).filter(Users.name == "tsb").first()
# con.query(Users).filter(Users.name == "tsb").update({"name": "sb", "age": 14})
r1 = con.query(Users).filter_by(name = "esb").first()
print(r1)
#必须提交才能生效
con.commit()
#关闭链接
con.close()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:@127.0.0.1:3307/python13", 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
session = Connection()
# 条件
# ret = session.query(Users).filter_by(name = "esb").all()
#表达式，and 条件链接
# ret = session.query(Users).filter(Users.name == "sb",Users.age ==14 ).first()
# print(ret.age,ret.name)
# 表示的between，条件,30<=age<=40
# ret = session.query(Users).filter(Users.age.between(30,40)).all()
# print(ret)
# sql查询的in_操作,相当于django中的__in
# ret =session.query(Users).filter(Users.id.in_([9,11,13])).all()
# print(ret)
# # sql查询取反
# ret1 = session.query(Users).filter(~Users.id.in_([9,11,13])).all()
# print(ret1)
#or查询 ，or和and ,做整合
from sqlalchemy import or_,and_
# ret = session.query(Users).filter(or_(Users.id == 9,Users.name=="jsb")).all()
# ret = session.query(Users).filter(and_(Users.id == 9,Users.name=="lsb1")).all()
# ret = session.query(Users).filter(or_(
# Users.id == 9,
# and_(Users.name=="jsb",Users.id==13),
#
# )
# ).all()
# like查询,
#必须以b开头
# ret = session.query(Users).filter(Users.name.like("b%")).all()
# #第二字母是b
# ret = session.query(Users).filter(Users.name.like("_b%")).all()
#不以b开头
# ret = session.query(Users).filter(~Users.name.like("b%")).all()
#排序
#desc重大到小排序
# ret = session.query(Users).filter(Users.id>1).order_by(Users.id.desc()).all()
#desc重小到大排序
#ret = session.query(Users).filter(Users.id>1).order_by(Users.id.asc()).all()
#多条件排序,先以年纪从大到小排，如果年龄相同，再以id从小到大排
# ret = session.query(Users).filter(Users.id>1).order_by(Users.age.desc(),Users.id.asc()).all()
# print(ret)
#分组查询
# ret = session.query(Users).group_by(Users.name).all()
# 再分组的时候如果要用聚合操作，就要导入func
from sqlalchemy.sql import func
#选出组内最小年龄要大于等于30的组
# ret = session.query(Users).group_by(Users.name).having(func.min(Users.age)>=30).all()
#选出组内最小年龄要大于等于30的组,查询组内的最小年龄，最大年纪，年纪之和，
ret = session.query(
func.min(Users.age),
func.max(Users.age),
func.sum(Users.age),
Users.name
).group_by(Users.name).having(func.min(Users.age)>=30).all()
print(ret)from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Hobby,Person
#"mysql+pymysql://root@127.0.0.1:3306/aaa"
engine = create_engine("mysql+pymysql://root:@127.0.0.1:3307/python13", 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
session = Connection()
#1添加,没有用关联关系
# session.add_all([
# Hobby(catption="淫诗"),
# Hobby(catption="推背"),
# Person(name="tank",hobby_id=1),
# Person(name="jason",hobby_id=2)
# ])
# 2添加 用关联关系
# preson = Person(name="egon",hobby=Hobby(catption="相亲"))
#session.add(preson)
#
# hobb = Hobby(catption="人妖")
# hobb.pres = [Person(name="owen"),Person(name="sean")]
# session.add(hobb)
#session.commit()
#正向查询
# pr = session.query(Person).filter( Person.name == "tank").first()
# print(pr.name)
# print(pr.hobby.catption)
#反向查
# v = session.query(Hobby).filter(Hobby.catption=="人妖").first()
# print(v.catption)
# print(v.pres)
# 自己连表,isouter=True表示是left join，不填默认为inner join
person_list = session.query( Hobby).join(Person,Person.hobby_id==Hobby.id,isouter=True)
#
print(person_list)
session.close()
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Boy,Boy2Girl,Girl
#"mysql+pymysql://root@127.0.0.1:3306/aaa"
engine = create_engine("mysql+pymysql://root:@127.0.0.1:3307/python13", 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
session = Connection()
#添加
# session.add_all([
# Boy(name="tank"),
# Boy(name="sean"),
# Girl(name="仓老师"),
# Girl(name="小泽老师")
# ])
# b2g = Boy2Girl(boy_id=1,girl_id=2)
# session.add(b2g )
# b2g = Boy2Girl(boy_id=2,girl_id=1)
# session.add(b2g )
# session.commit()
# session.close()
#
# boy = Boy(name="亚峰")
# boy.girl=[Girl(name="迪丽热巴"),Girl(name="三上")]
# session.add(boy)
# session.commit()
#
# girl = Girl(name="丹丹")
# girl.boys=[Boy(name="吴彦祖"),Boy(name="鹿晗")]
# session.add(girl)
# session.commit()
# 使用relationship的关系，正向查
# b = session.query(Boy).filter(Boy.name == "亚峰").first()
# print(b.name)
# print(b.girl)
#反向查询
# g = session.query(Girl).filter(Girl.name=="丹丹").first()
# print(g.name)
# print(g.boys)要用就必须先安装。
所有的到导入都找 下面的db
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()命令：manager.add_command('db1', MigrateCommand)
1 当项目第一次执行迁移的时候。
python3 manage.py db1 init 只需要初始化一次
2 python3 manage.py db1 migrate # 等同于django的makemigrations
3 python3 manage.py db1 upgrade # 等同于django的migrate标签：删除数据库 and 报错 filter str 记录 pytho 过滤 添加
原文地址：https://www.cnblogs.com/kai-/p/12540520.html
