Python kann nicht fangen pymssql Exception

Question

Die try/except nicht die angegebene pymssql Ausnahme im folgenden Ausschnitt erfassen:

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" 

Traceback:

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'] 

Die Database Klasse ist nur eine einfache Möglichkeit, um auf einige häufig verwendete Datenbanken zuzugreifen, mit denen ich arbeiten muss. Es gibt das Datenbankverbindungsmodul db_cnxn zurück. Wie Sie im Traceback sehen können, ist dies ein sqlalchemy.engine.base.Engine-Objekt.

das gesamte pymssql Paket importieren, wie unten gezeigt erzeugt die gleiche Zurückverfolgungs:

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" 

Bitte um Hilfe! Vielen Dank.

Answer 1

Da Sie sqlalchemy verwenden, ist dies diejenige, die Sie interessiert sind, nicht die pymssql ein:

from sqlalchemy.exc import ProgrammingError