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How to Create a Database

How to Create a Database

We'll cover the following...

Creating a database with SQLAlchemy is really easy. SQLAlchemy uses a Declarative method for creating databases. We will write some code to generate the database and then explain how the code works. If you want a way to view your SQLite database, I would recommend the SQLite Manager plugin for Firefox. Here’s some code to create our database tables:

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# table_def.py
from sqlalchemy import create_engine, ForeignKey
from sqlalchemy import Column, Date, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship, backref
engine = create_engine('sqlite:///mymusic.db', echo=True)
Base = declarative_base()
class Artist(Base):
    """"""
    __tablename__ = "artists"
    id = Column(Integer, primary_key=True)
    name = Column(String)  
class Album(Base):
    """"""
    __tablename__ = "albums"
    id = Column(Integer, primary_key=True)
    title = Column(String)
    release_date = Column(Date)
    publisher = Column(String)
    media_type = Column(String)
    artist_id = Column(Integer, ForeignKey("artists.id"))
    artist = relationship("Artist", backref=backref("albums", order_by=id))
# create tables
Base.metadata.create_all(engine)

If you run this code, then you should see something similar to the following output:

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2014-04-03 09:43:57,541 INFO sqlalchemy.engine.base.Engine SELECT CAST('test plain returns' AS VARCHAR(60)) AS anon_1
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine ()
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine SELECT CAST('test unicode returns' AS VARCHAR(60)) AS anon_1
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine ()
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine PRAGMA table_info("artists")
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine ()
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine PRAGMA table_info("albums")
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine ()
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine
CREATE TABLE artists (
    id INTEGER NOT NULL,
    name VARCHAR,
    PRIMARY KEY (id)
)
2014-04-03 09:43:57,551 INFO sqlalchemy.engine.base.Engine ()
2014-04-03 09:43:57,661 INFO sqlalchemy.engine.base.Engine COMMIT
2014-04-03 09:43:57,661 INFO sqlalchemy.engine.base.Engine
CREATE TABLE albums (
    id INTEGER NOT NULL,
    title VARCHAR,
    release_date DATE,
    publisher VARCHAR,
    media_type VARCHAR,
    artist_id INTEGER,
    PRIMARY KEY (id),
    FOREIGN KEY(artist_id) REFERENCES artists (id)
)
2014-04-03 09:43:57,661 INFO sqlalchemy.engine.base.Engine ()
2014-04-03 09:43:57,741 INFO sqlalchemy.engine.base.Engine COMMIT

Why did this happen? Because when we created the engine ...