第二十章、 数据库编程
环境设置
1).安装MySQL-python
http://www.lfd.uci.edu/~gohlke/pythonlibs/
MySQL-python-1.2.3.win32-py2.7.exe
1) 使用数据库接口
import MySQLdb
cxn = MySQLdb.Connect(host = '127.0.0.1', user = 'root', passwd = 'root')
cur = cxn.cursor()
try:
cur.execute("DROP DATABASE test610")
except Exception, e:
print e.args;
finally:
pass
cur.execute("CREATE DATABASE test610")
cur.execute("USE test610")
cur.execute("CREATE TABLE users (id INT, name VARCHAR(8))")
cur.execute("INSERT INTO users VALUES(10, 'tao')")
cur.execute("INSERT INTO users VALUES(20, 'jin')")
cur.execute("INSERT INTO users VALUES(31, 'dan')")
cur.execute("UPDATE users SET name = 'jim' WHERE id = 20")
cur.execute("SELECT * FROM users")
for row in cur.fetchall():
print '%s\t%s' %row
cur.close()
cxn.commit()
cxn.close()
2) 使用ORM_SQLalchemy
环境设置
安装SQLalchemy(SQLAlchemy-0.7.1.tar.gz)
下载http://www.sqlalchemy.org/download.html
解压放到python安装目录下的lib目录里
D:\Python27\Lib\SQLAlchemy-0.7.1>python setup.py install
from sqlalchemy import *
##Precondition：database 'test0615' do exist!
engine = create_engine('mysql://root:root@localhost/test0615')
##Define and Create Tables
metadata = MetaData()
users = Table('users', metadata,
Column('id', Integer, primary_key=True),
Column('name', String(10)),
Column('fullname', String(20)),
)
address = Table('address', metadata,
Column('id', Integer, primary_key=True),
Column('user_id', None, ForeignKey('users.id')),
Column('email', String(20), nullable=False)
)
metadata.create_all(engine, checkfirst = True)
##Insert Expressions
#method 1
ins = users.insert().values(name='Jim', fullname='Jim T')
conn = engine.connect()
result = conn.execute(ins)
#method 2
result = engine.execute(users.insert(), name='fred', fullname="Fred F")
#method 3
metadata.bind = engine
result = users.insert().execute(name="mary", fullname="Mary C")
metadata.bind = None
#method 4
conn.execute(address.insert(), [
{'user_id': 1, 'email' : 'jack@yao.com'},
{'user_id': 2, 'email' : 'wedy@aol.com'},
])
##Selecting
s = select([users])
result = conn.execute(s)
#method 1
for row in result:
print row
#method 2
s = select([users, address], users.c.id==address.c.user_id)
for row in conn.execute(s):
print row
##Updates
conn.execute(users.update().
where(users.c.name == 'jack').
values(name = 'ed')
)
##Deletes
conn.execute(address.delete().where(address.c.id > 20))
conn.execute(users.delete().where(users.c.name > 'm'))
##遗留问题,无法关闭数据库连接
##metadata.drop_all(engine, [users, address], checkfirst = False)
3) 使用ORM_SQLObject
环境设置
安装FormEncode (FormEncode-1.2.4.tar.gz)
下载http://pypi.python.org/pypi/FormEncode
解压放到python安装目录下的lib目录里
D:\Python27\Lib\FormEncode-1.2.4>python setup.py install
安装SQLObject (SQLObject-1.0.1.tar.gz)
下载http://pypi.python.org/pypi/SQLObject
解压放到python安装目录下的lib目录里
D:\Python27\Lib\SQLObject-1.0.1>python setup.py install
#!/usr/bin/env python
import os
import MySQLdb
import _mysql_exceptions
from sqlobject import *
DBNAME = 'database0615'
url = 'mysql://root:root@localhost/%s' % DBNAME
COLSIZ = 10
FIELDS = ('firstName', 'middleInitial', 'lastName')
cxn1 = sqlhub.processConnection = connectionForURI(url)
cxn1.query("DROP DATABASE %s" % DBNAME)
cxn1.query("CREATE DATABASE %s" % DBNAME)
cxn1.close()
try:
class Person(SQLObject):
firstName = StringCol()
middleInitial = StringCol(length=1, default=None)
lastName = StringCol()
Person.createTable()
except NameError, e:
pass
#make SQLObject print out the SQL it executes
Person._connection.debug = False
#Insert
p1 = Person(firstName = "John", lastName = "Doe")
p2 = Person(firstName = "Jin", lastName = "Tao")
p3 = Person(firstName = "Dan", lastName = "Tao")
p4 = Person(firstName = "Joan", lastName = "Wu")
#Select
print p2.lastName, p2.firstName
print list(Person.select(AND(Person.q.lastName == "Tao",
Person.q.firstName == "Jin")))
#Update
p1.middleInitial = 'S'
p3.middleInitial = 'T'
p2.lastName = 'Hu'
#Delete
Person.delete(p1.id)
for row in Person.select():
print '%s%s%s' % (tuple([str(getattr(row,
field)).title().ljust(COLSIZ) for field in FIELDS]))
Person.deleteBy()