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  • python 教程 第二十章、 数据库编程

    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	%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:Python27LibSQLAlchemy-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:Python27LibFormEncode-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:Python27LibSQLObject-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() 
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  • 原文地址:https://www.cnblogs.com/lanzhi/p/6468786.html
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