本文研究的主要是python通过elixir包操作mysql数据库的相关实例，具体如下。

python操作数据库有很多方法，下面介绍elixir来操作数据库。elixir是对sqlalchemy lib的一个封装，classes和tables是一一对应的，能够一步定义classes，tables和mappers，支持定义多个primary key。

定义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()

执行model.py，结果为：

查看数据库，结果为：

总结

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