Python: SQL Alchemy

sqlalchemy learning notes

so, it's a object relational shit.

but, basically, you just create a class/object in python, and each such corresponds to a table table. the in the class, the properties are just tablle columnns. Then, each instance of the class is different rows.

some like that.

http://docs.sqlalchemy.org/en/rel_0_9/orm/tutorial.html

show version

import sqlalchemy
sqlalchemy.__version__
# 0.9.0

To connect we use create_engine():

from sqlalchemy import create_engine
engine = create_engine('sqlite:///:memory:', echo=True)

The return value of create_engine() is an instance of Engine, and it represents the core interface to the database,

The first time a method like Engine.execute() or Engine.connect() is called, the Engine establishes a real DBAPI connection to the database, which is then used to emit the SQL. When using the ORM, we typically don't use the Engine directly once created; instead, it's used behind the scenes by the ORM as we’ll see shortly.

declare mapping

declare base, then create a table schema

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

from sqlalchemy import Column, Integer, String
class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String)
    fullname = Column(String)
    password = Column(String)

    def __repr__(self):
       return "<User(name='%s', fullname='%s', password='%s')>" % (
                            self.name, self.fullname, self.password)