Python连接Oracle数据库的实用方法与封装类实现

conn=cx_Oracle.connect('用户名','密码','数据库地址:数据库端口/SID')

conn=cx_Oracle.connect('用户名/密码@数据库地址:数据库端口/SID')

conn=cx_Oracle.connect('用户名','密码',tns)

tns=cx_Oracle.makedsn('数据库地址','数据库端口', 'SID')

tns = '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=KGDB)))'
conn = cx_Oracle.connect('nicker', '123456', tns)

#coding:utf-8
import cx_Oracle
# 创建数据库连接
# cx_Oracle.connect('username','pwd','ora的tns信息')
# oracle数据库的tns信息，从tnsnames.ora中找到plsql可用的配置项，将该配置项直接拷贝过来即可
ora_tns = '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=KGDB)))'
conn = cx_Oracle.connect('nicker', '123456', ora_tns)
# 操作游标
cursor = conn.cursor()
# 执行查询
cursor.execute("SELECT * FROM inst_info")
# 获取返回信息
rs = cursor.fetchall()
# 输出信息
for v in rs:
  print v
#关闭连接，释放资源
cursor.close()
conn.close()

#coding:utf-8
import cx_Oracle
# 封装的类
class cxOracle:
  '''
  tns的取值tnsnames.ora对应的配置项的值，如：
  tns = '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=10.16.18.23)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=MYDB)))'
  '''
  def __init__(self ,uname, upwd,tns ):
    self ._uname = uname
    self ._upwd = upwd
    self ._tns = tns
    self ._conn = None
    self ._ReConnect()
  def _ReConnect(self ):
    if not self._conn :
      self ._conn = cx_Oracle.connect (self. _uname, self ._upwd, self._tns)
    else:
      pass
  def __del__(self ):
    if self. _conn:
      self ._conn. close()
      self ._conn = None
  def _NewCursor(self ):
    cur = self. _conn.cursor ()
    if cur:
      return cur
    else:
      print "#Error# Get New Cursor Failed."
      return None
  def _DelCursor(self , cur):
    if cur:
      cur .close()
  # 检查是否允许执行的sql语句
  def _PermitedUpdateSql(self ,sql):
    rt = True
    lrsql = sql. lower()
    sql_elems = [ lrsql.strip ().split()]
    # update和delete最少有四个单词项
    if len( sql_elems) < 4 :
      rt = False
    # 更新删除语句，判断首单词，不带where语句的sql不予执行
    elif sql_elems[0] in [ 'update', 'delete']:
      if 'where' not in sql_elems :
        rt = False
    return rt
  # 导出结果为文件
  def Export(self , sql, file_name, colfg ='||'):
    rt = self. Query(sql )
    if rt:
      with open( file_name, 'a') as fd:
        for row in rt:
          ln_info = ''
          for col in row:
             ln_info += str( col) + colfg
          ln_info += '\n'
          fd .write( ln_info)
  # 查询
  def Query(self , sql, nStart=0 , nNum=- 1):
    rt = []
    # 获取cursor
    cur = self. _NewCursor()
    if not cur:
      return rt
    # 查询到列表
    cur .execute(sql)
    if ( nStart==0 ) and (nNum==1 ):
      rt .append( cur.fetchone ())
    else:
      rs = cur. fetchall()
      if nNum==- 1:
        rt .extend( rs[nStart:])
      else:
        rt .extend( rs[nStart:nStart +nNum])
    # 释放cursor
    self ._DelCursor(cur)
    return rt
  # 更新
  def Exec(self ,sql):
    # 获取cursor
    rt = None
    cur = self. _NewCursor()
    if not cur:
      return rt
    # 判断sql是否允许其执行
    if not _PermitedUpdateSql(sql ):
      return rt
    # 执行语句
    rt = cur. execute(sql )
    # 释放cursor
    self ._DelCursor(cur)
    return rt
# 类使用示例
tns = '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=10.16.17.46)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=MYDB)))'
ora = cxOracle ('nicker', '123456', tns)
# 导出结果为文件
rs = ora .Export("SELECT * FROM org", '1.txt')
# 查询结果到列表
rs = ora.Query("SELECT * FROM org")
print rs
# 更新数据
ora.Exec("update org set org_name='NewNameForUpdate' where org_id=123456;")