cx_Oracle使用方法[转]

 

From: http://hi.baidu.com/piter2010/blog/item/47bbbacbfa0efe16be09e6a0.html

 

正确安装好cx_oracle之后，要使用它来连接到oracle数据库进行操作，具体应该分3步走： 第一步：导入cx_Oracle，建立连接 >>>  import cx_Oracle      # 导入模块 >>>  db = cx_Oracle.connect('hr', 'hrpwd', 'localhost:1521/XE')  建立连接，3 个参数分开写 特别注意：这里的 'localhost:1521/XE'可以是你oracle net manager配置的链接名，如oracl，我就是在这里耽搁了半天 >>>  db1 = cx_Oracle.connect('hr/hrpwd@localhost:1521/XE')  建立连接，3 个参数连写 >>>  dsn_tns = cx_Oracle.makedsn('localhost', 1521, 'XE') >>>  print dsn_tns (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))) (CONNECT_DATA=(SID=XE))) >>>  db2 = cx_Oracle.connect('hr', 'hrpwd', dsn_tns) >>> <strong style="line-height: normal;">print db.version</strong><br style="line-height: normal;" /> 10.2.0.1.0<br style="line-height: normal;" /> >>> <strong style="line-height: normal;">versioning = db.version.split('.')</strong><br style="line-height: normal;" /> >>> <strong style="line-height: normal;">print versioning</strong><br style="line-height: normal;" /> ['10', '2', '0', '1', '0']<br style="line-height: normal;" /> >>> <strong style="line-height: normal;">if versioning[0]=='10':</strong><br style="line-height: normal;" /> ...     <strong style="line-height: normal;">print "Running 10g"</strong><br style="line-height: normal;" /> ... <strong style="line-height: normal;">elif versioning[0]=='9':</strong><br style="line-height: normal;" /> ...    <strong style="line-height: normal;">print "Running 9i"</strong><br style="line-height: normal;" /> ...<br style="line-height: normal;" /> Running 10g<br style="line-height: normal;" /> >>> <strong style="line-height: normal;">print db.dsn</strong><br style="line-height: normal;" /> localhost:1521/XE 第二步：建立 Cursor 光标 >>>cursor = db.cursor() 建立一个cursor 之后，我们可以调用这个cursor.execute（‘SQL‘） 来执行SQL语句。比如： >>>cursor.execute(‘select * from tabs’) 执行完毕以后，可以调用cursor.fetchall()一次取完所有结果，或者cursor.fetchone()一次取一行结果 >>>row=cursor.fetchall() >>>for x in row:       For y in x:          Print y,        Print 这样就可以按照表格的形式打印取得的结果了！ 在从oracle取出数据的时候，考虑到它的数据类型了吗？下面就是数据类型的对应表 Datatypes During the fetch stage, basic Oracle data types get mapped into their Python equivalents. cx_Oracle maintains a separate set of data types that helps in this transition. The Oracle - cx_Oracle - Python mappings are: Oracle cx_Oracle Python VARCHAR2 NVARCHAR2 LONG cx_Oracle.STRING str CHAR cx_Oracle.FIXED_CHAR NUMBER cx_Oracle.NUMBER int FLOAT float DATE cx_Oracle.DATETIME datetime.datetime TIMESTAMP cx_Oracle.TIMESTAMP CLOB cx_Oracle.CLOB cx_Oracle.LOB BLOB cx_Oracle.BLOB 带参数的查询： >>> named_params = {'dept_id':50, 'sal':1000} >>> query1 = cursor.execute('SELECT * FROM employees  WHERE department_id=:dept_id AND salary>:sal', named_params) >>> query2 = cursor.execute('SELECT * FROM employees  WHERE department_id=:dept_id AND salary>:sal', dept_id=50, sal=1000) 这种是名字参数，还可以按位置参数： r1 = cursor.execute('SELECT * FROM locations  WHERE country_id=:1 AND city=:2', ('US', 'Seattle')) 注意： 当只有一次参数的时候，也要把它写成元组的形式，比如 Cursor.execute(‘select name from user where id=:1’,(login_Id,)) 千万要注意，login_id后面还带有一个逗号，如果没有逗号，他其实就是一个数据对象，但是当他后面有个逗号的时候，他就变成了元组的一个数据项，千万要记住啊，我就是在这里徘徊了很久。！ Cursor. Prepare的用法， 这个方法就是在prepare之后，你再去execute的时候，就不用写上sql语句参数了 >>> cursor.prepare('SELECT * FROM jobs WHERE min_salary>:min') >>> r = cursor.execute(None, {'min':1000}) #注意，第一个参数是None, 一次执行多条sql语句 Large insert operations don't require many separate inserts because Python fully supports inserting many rows at once with the cx_Oracle.Cursor.executemany method. Limiting the number of execute operations improves program performance a lot and should be the first thing to think about when writing applications heavy on INSERTs. Let's create a table for a Python module list, this time directly from Python. You will drop it later. >>> create_table = """<br style="line-height: normal;" /> CREATE TABLE python_modules (<br style="line-height: normal;" /> module_name VARCHAR2(50) NOT NULL,<br style="line-height: normal;" /> file_path VARCHAR2(300) NOT NULL<br style="line-height: normal;" /> )<br style="line-height: normal;" /> """<br style="line-height: normal;" /> >>> from sys import modules<br style="line-height: normal;" /> >>> cursor.execute(create_table)<br style="line-height: normal;" /> >>> M = []<br style="line-height: normal;" /> >>> for m_name, m_info in modules.items():<br style="line-height: normal;" /> ...   try:<br style="line-height: normal;" /> ...     M.append((m_name, m_info.__file__))<br style="line-height: normal;" /> ...   except AttributeError:<br style="line-height: normal;" /> ...     pass<br style="line-height: normal;" /> ...<br style="line-height: normal;" /> >>> len(M)<br style="line-height: normal;" /> 76<br style="line-height: normal;" /> >>> cursor.prepare("INSERT INTO python_modules(module_name, file_path) VALUES (:1, :2)")<br style="line-height: normal;" /> >>> cursor.executemany(None, M)<br style="line-height: normal;" /> >>> db.commit()<br style="line-height: normal;" /> >>> r = cursor.execute("SELECT COUNT(*) FROM python_modules")<br style="line-height: normal;" /> >>> print cursor.fetchone()<br style="line-height: normal;" /> (76,)<br style="line-height: normal;" /> >>> cursor.execute("DROP TABLE python_modules PURGE")