Python不能赶上pymssql异常

Question

在try /除了没有捕捉指定的pymssql例外，下面的代码片段：

import pandas as pd 
from fps.databaseconnections import DatabaseConnections 
from pymssql import ProgrammingError 

DatabaseConnections_instance = DatabaseConnections() 
db_cnxn = DatabaseConnections_instance.get_connection("gtaemndprod") 

print "\ndb_cnxn is this class: {}\n".format(db_cnxn.__class__) 

try: 
    pd.read_sql("SELECT blah",db_cnxn) 
except ProgrammingError: 
    print "A" 

回溯：

db_cnxn is this class: <class 'sqlalchemy.engine.base.Engine'> 

Traceback (most recent call last): 

    File "<ipython-input-20-9e8944849cfd>", line 11, in <module> 
pd.read_sql("SELECT blah",db_cnxn) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\pandas\io\sql.py", line 515, in read_sql 
chunksize=chunksize) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\pandas\io\sql.py", line 1190, in read_query 
result = self.execute(*args) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\pandas\io\sql.py", line 1081, in execute 
return self.connectable.execute(*args, **kwargs) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\engine\base.py", line 1991, in execute 
return connection.execute(statement, *multiparams, **params) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\engine\base.py", line 906, in execute 
return self._execute_text(object, multiparams, params) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\engine\base.py", line 1054, in _execute_text 
statement, parameters 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\engine\base.py", line 1146, in _execute_context 
context) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\engine\base.py", line 1341, in _handle_dbapi_exception 
exc_info 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\util\compat.py", line 202, in raise_from_cause 
reraise(type(exception), exception, tb=exc_tb, cause=cause) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\engine\base.py", line 1139, in _execute_context 
context) 

    File "C:\Users\212476924\AppData\Local\Continuum\Anaconda2\lib\site-packages\sqlalchemy\engine\default.py", line 450, in do_execute 
cursor.execute(statement, parameters) 

    File "pymssql.pyx", line 464, in pymssql.Cursor.execute (pymssql.c:7491) 

ProgrammingError: (pymssql.ProgrammingError) (207, "Invalid column name 'blah'.DB-Lib error message 20018, severity 16:\nGeneral SQL Server error: Check messages from the SQL Server\n") [SQL: 'SELECT blah'] 

的DatabaseConnections类只是一个简单的方法访问我需要使用的一些常用数据库。它返回数据库连接引擎db_cnxn。正如你在traceback中看到的，这是一个sqlalchemy.engine.base.Engine对象。

导入，如下图所示，整个pymssql包产生相同的回溯：

import pandas as pd 
from fps.databaseconnections import DatabaseConnections 
import pymssql 

DatabaseConnections_instance = DatabaseConnections() 
db_cnxn = DatabaseConnections_instance.get_connection("gtaemndprod") 

print "\ndb_cnxn is this class: {}\n".format(db_cnxn.__class__) 

try: 
    pd.read_sql("SELECT blah",db_cnxn) 
except pymssql.ProgrammingError: 
    print "A" 

请帮帮忙！谢谢。

Answer 1

由于您使用sqlalchemy，这是一个你有兴趣，而不是pymssql一个：

from sqlalchemy.exc import ProgrammingError