sqlalchemy

from sqlalchemy import Column, String, Integer, ForeignKey
from sqlalchemy.orm import relationship, sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine

Base = declarative_base()


class Department(Base):
    __tablename__ = 'department'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    employees = relationship('Employee', secondary='department_employee')


class Employee(Base):
    __tablename__ = 'employee'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    departments = relationship('Department', secondary='department_employee')


class DepartmentEmployee(Base):
    __tablename__ = 'department_employee'
    department_id = Column(Integer, ForeignKey('department.id'), primary_key=True)
    employee_id = Column(Integer, ForeignKey('employee.id'), primary_key=True)


engine = create_engine('sqlite:///department_store2.db')
session = sessionmaker()
session.configure(bind=engine)
# Base.metadata.create_all(engine)

s = session()
m = s.query(Employee).filter(Employee.name == 'Mary').one()
i = s.query(Department).filter(Department.name == 'IT').one()

s.delete(m.departments.filter(Department.name == 'IT'))
s.add(m)
s.commit()