SQLAlchemy

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String

# Base = ORM基类 - 要按照ORM的规则定义你的类
Base = declarative_base()

class Users(Base):
    __tablename__ = "user"
    # 创建ID数据字段 , 那么ID是不是一个数据列呢? 也就是说创建ID字段 == 创建ID数据列
    # id = Column(数据类型,索引,主键,外键,等等)
    id = Column(Integer, primary_key=True, autoincrement=True,index=True)
    name = Column(String(32), nullable=False)  # nullable=False 不能为空


# 打开数据库的连接 -- 创建数据库引擎
from sqlalchemy import create_engine
# 创建数据库引擎
# engine = create_engine("mysql://scott:tiger@hostname/dbname",encoding=‘latin1‘, echo=True)
engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/SQLAlchemy_Pro?charset=utf8")

Base.metadata.create_all(engine)  # Base自动检索所有继承Base的ORM 对象 并且创建所有的数据表

from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()

from sqlalchemy import Column,Integer,String,ForeignKey
from sqlalchemy.orm import relationship

class Student(Base):
    __tablename__ = "student"
    id = Column(Integer,primary_key=True)
    name = Column(String(32),nullable=False)
    sch_id = Column(Integer,ForeignKey("school.id"))  # 关联的表的字段,表间的关系

    stu2sch = relationship("School",backref="sch2stu")  # 写在哪边那边就是正向查询，对象间的关系，backref(反向查询)


class School(Base):
    __tablename__ = "school"
    id = Column(Integer,primary_key=True)
    name = Column(String(32),nullable=False)


from sqlalchemy import create_engine
engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/SQLAlchemy_Pro?charset=utf8")

Base.metadata.create_all(engine)

from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from creatTable import Users

# 创建引擎
engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/SQLAlchemy_Pro?charset=utf8")

Session = sessionmaker(engine)
db_session = Session()

# 1. 增加数据add(创建表结构的类名(字段名=添加的数据))
db_session.add(Users(name="ZWQ"))  # 相当于建立一条添加数据的sql语句
db_session.commit()  # 执行
db_session.close()   # 结束关闭

# 批量添加
db_session.add_all([Users(name="清风徐来"), Users(name="水波不兴")])
db_session.commit()
db_session.close()

# 2.查询 query(表结构的类名)
sqlres = db_session.query(Users)
print(sqlres)  # 直接翻译输出对应的SQL查询语句

res = db_session.query(Users).all()  # 返回表中所有数据对象
print(res)# [<creatTable.Users object at 0x00000000038A1B00>,<creatTable.Users object at 0x00000000038A1B70>]

for u in res:
    print(u.id, u.name)

res = db_session.query(Users).first()  # 取第一个，返回是对象
print(res.id, res.name)

res = db_session.query(Users).filter(Users.id == 3).first()  # 返回符合条件查询结果
print(res.name)

res = db_session.query(Users).filter(Users.id <= 2, Users.name == "ZWQ").all() # filter中的条件可以是模糊条件,多个条件
for u in res:
    print(u.id,u.name)

# 3.更改数据 update({k:v})
res = db_session.query(Users).filter(Users.id == 1).update({"name":"DragonFire"})
print(res)
db_session.commit()

res = db_session.query(Users).update({"name":"ZWQ"})  # 全部修改，返回修改的数据个数
print(res)
db_session.commit()

# 4.删除 delete()结合查询条件删除
res = db_session.query(Users).filter(Users.id == 1).delete()  # 删除否合条件的数据，返回删除数量
print(res)
db_session.commit()

res = db_session.query(Users).delete()  # 删除表中所有数据，返回删除数量
print(res)
db_session.commit()