本文研究的主要是python通過elixir包操作mysql資料庫的相關例項，具體如下。

python操作資料庫有很多方法，下面介紹elixir來操作資料庫。elixir是對sqlalchemy lib的一個封裝，classes和tables是一一對應的，能夠一步定義classes，tables和mappers，支援定義多個primary key。

定義model.py

from elixir import sqlalchemy 
from elixir import * 
 
engine =sqlalchemy.create_engine('mysql://root:root@localhost/') #the first root is the user,and the sencond root is the password 
#engine.execute("DROP DATABASE IF EXISTS elixir") 
engine.execute("CREATE DATABASE IF NOT EXISTS elixir") 
 
 
metadata.bind='mysql://root:root@localhost:3306/elixir' 
#metadata.bind.echo =True 
class Movie(Entity): 
  using_options(tablename='movies') 
 
  title = Field(Unicode(30),primary_key = True) 
  year = Field(Integer,primary_key = True) 
  description = Field(UnicodeText) 
  director = ManyToOne('Director') 
  genres = ManyToMany('Genre') 
  actor = ManyToMany('Actor') 
 
  def __repr__(self): 
    return '<Move "%s" (%d)>' % (self.title,self.year) 
 
class Person(Entity): 
  using_options(inheritance='multi') 
  using_options(tablename='person') 
 
  name = Field(Unicode(60)) 
 
  def __repr__(self): 
    return '<Person "%s">' % self.name 
 
 
class Director(Person): 
  using_options(inheritance='multi') 
  using_options(tablename='director') 
 
  movies = OneToMany('Movie') 
 
  def __repr__(self): 
    return '<Director "%s">' % self.name 
 
class Genre(Person): 
  using_options(inheritance='multi') 
  using_options(tablename='genre') 
 
  movies = ManyToMany('Movie') 
 
  def __repr__(self): 
    return '<Genre "%s">' % self.name 
 
class Actor(Person): 
  using_options(inheritance='multi') 
  using_options(tablename='actor') 
 
  movies = ManyToMany('Movie') 
 
  def __repr__(self): 
    return '<Actor "%s">' % self.name 

model_test.py

from model import * 
 
# setup_all(True) is equal to the following two staps: 
setup_all() # create sqlalchemy table object as mapper object for the class 
create_all() # take all table objcts and create real tables by issuing SQL statements on the databse. 
 
Actor1 = Actor(name=u"lvliang") 
scifi = Genre(name = u"Science-Fiction") 
rscott = Director(name = u"Ridley Scott") 
glucas = Director(name = u"George Lucas") 
alien = Movie(title = u"Alien",year = 1979,director=rscott,genres=[scifi,Genre(name=u"Horror")],actor = [Actor1]) 
brunner = Movie(title = u"Blade Runner",year = 1982,director = rscott,genres=[scifi]) 
swars = Movie(title = u"Star Wars",year = 1977,director = glucas,genres=[scifi]) 
session.commit() 
 
 
m1 = Movie.query.filter_by(title=u"Alien").one() 
m2 = Movie.query.filter(Movie.year>1980).all() 
m3 = Movie.query.filter(Movie.director.has(name = u"Ridley Scott")).all() 
m4 = Movie.query.filter(Movie.director.has(Director.name.endswith(u"Scott"))).all() 
m5 = Movie.query.filter(Movie.genres.any(name = u"Horror")).all() 
 
print m1 
print m2 
print m3 
print m4 
print m5 
 
d = Director.get_by(name = u"Ridley Scott") # Class.get_by(xxx) is a shortcut for Class.query.filter_by(xxx).first 
q = Movie.query.filter_by(director = d) #get all movies directed by director d 
m = q.filter_by(year = 1979).all() 
print "Movie direct by %s in year 1979 are " %(d.name) 
print m 
 
movies = q.order_by(sqlalchemy.desc(Movie.year)).all() 
print movies 
fro m in movies: 
  m.delete() 
session.commit() 

執行model.py，結果為：

檢視資料庫，結果為：

總結

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