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How do I access AS/400 using SQLAlchemy?
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Solved pythonsqlalchemypyodbcdb2-400
S

1

6

Short version: Please tell me how to connect to AS/400s via SQLAlchemy.

Long version

My ultimate goal is to join data from SQL Server and AS/400 to be displayed in a Flask Python application. My approach has been to get the data from each database into Pandas dataframes, which can then be joined and output as JSON. If anyone has a better approach, feel free to leave a comment. The problem with the way I'm trying to do this is that Pandas.read_sql_query() relies on SQLAlchemy, and getting SQLAlchemy to work with AS/400 is proving quite difficult.

  • The AS/400 is version 7.2, though another I will likely try to connect to is version 5.1.
  • I'm trying to access it from my computer, which is running Windows 7 and has i Access 7.1, Python 2.7, and Python modules including pyodbc and ibm_db_sa.

Without sqlalchemy, pyodbc works just fine:

CONNECTION_STRING = (
    "driver={iSeries Access ODBC Driver};"
    "system=ip_address;"
    "database=database_name;"
    "uid=username;"
    "pwd=password;"
) 
pyodbc.connect(CONNECTION_STRING)
# Queries work fine after this.

I've read these resources, among others, and tried to apply their techniques:

Below are some of the failed attempts and corresponding error messages that I've collected. I don't know what to put for the first part ("something+something//..."), which port to specify (446? 8471? something else? nothing?), whether to use the server's name or IP address, or whether to use the connection-string style argument for create_engine(), so I've just been trying every combination I can think of. I tried modifying the AS400Dialect_pyodbc class as suggested in the second link above, after which I tried rerunning some of the failed attempts again. I may keep trying things, but I'm just spinning my wheels at this point.

from sqlalchemy import create_engine

CONNECTION_STRING = (
    "driver={iSeries Access ODBC Driver};"
    "system=ip_address;"
    "database=database_name;"
    "uid=username;"
    "pwd=password;"
)

create_engine('ibm_db_sa+pyodbc://username:password@ip_address:446/database_name').connect()

Exception has occurred: sqlalchemy.exc.InterfaceError (pyodbc.InterfaceError) ('IM002', u'[IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified (0) (SQLDriverConnect)') (Background on this error at: http://sqlalche.me/e/rvf5) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 43, in 

create_engine('ibm_db_sa://username:password@ip_address:446/database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL30061N The database alias or database name "database_name " was not found at the remote node. SQLSTATE=08004\r SQLCODE=-30061 (Background on this error at: http://sqlalche.me/e/e3q8) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 43, in 

create_engine('ibm_db_sa://username:password@server_name:446/database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL1336N The remote host "server_name" was not found. SQLSTATE=08001\r SQLCODE=-1336 (Background on this error at: http://sqlalche.me/e/e3q8create_engine('ibm_db_sa://username:password@ip_address:446/server_name.database_name').connect()

create_engine('ibm_db_sa://username:password@ip_address:446/server_name.database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL30061N The database alias or database name "server_name.database_name " was not found at the remote node. SQLSTATE=08004\r SQLCODE=-30061 (Background on this error at: http://sqlalche.me/e/e3q8)

create_engine('db2+ibm_db://username:password@ip_address:446/server_name.database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL30061N The database alias or database name "server_name.database_name " was not found at the remote node. SQLSTATE=08004\r SQLCODE=-30061 (Background on this error at: http://sqlalche.me/e/e3q8) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 45, in 

create_engine('db2+ibm_db://username:password@ip_address:446/database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL30061N The database alias or database name "database_name " was not found at the remote node. SQLSTATE=08004\r SQLCODE=-30061 (Background on this error at: http://sqlalche.me/e/e3q8) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 45, in 

create_engine('db2+ibm_db://username:password@ip_address/database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL30081N A communication error has been detected. Communication protocol being used: "TCP/IP". Communication API being used: "SOCKETS". Location where the error was detected: "ip_address". Communication function detecting the error: "connect". Protocol specific error code(s): "10061", "", "". SQLSTATE=08001\r SQLCODE=-30081 (Background on this error at: http://sqlalche.me/e/e3q8)

create_engine('db2+ibm_db://username:password@server_name:446/database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL1336N The remote host "server_name" was not found. SQLSTATE=08001\r SQLCODE=-1336 (Background on this error at: http://sqlalche.me/e/e3q8)

create_engine('db2+ibm_db://username:password@server_name/database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL1336N The remote host "server_name" was not found. SQLSTATE=08001\r SQLCODE=-1336 (Background on this error at: http://sqlalche.me/e/e3q8)

create_engine('db2+pyodbc://username:password@ip_address:446/database_name').connect()

Exception has occurred: sqlalchemy.exc.InterfaceError (pyodbc.InterfaceError) ('IM002', u'[IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified (0) (SQLDriverConnect)') (Background on this error at: http://sqlalche.me/e/rvf5) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 45, in 

create_engine('db2://username:password@ip_address:446/database_name').connect()

Exception has occurred: sqlalchemy.exc.OperationalError (ibm_db_dbi.OperationalError) ibm_db_dbi::OperationalError: [IBM][CLI Driver] SQL30061N The database alias or database name "database_name " was not found at the remote node. SQLSTATE=08004\r SQLCODE=-30061 (Background on this error at: http://sqlalche.me/e/e3q8) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 45, in 

quoted = urllib.quote_plus(CONNECTION_STRING)
create_engine('ibm_db_sa+pyodbc:///?odbc_connect={}'.format(quoted)).connect()

Unable to open 'hashtable_class_helper.pxi': File not found (file:///c:/git/dashboards/pandas/_libs/hashtable_class_helper.pxi).

quoted = urllib.quote_plus(CONNECTION_STRING)
create_engine('ibm_db_sa:///?odbc_connect={}'.format(quoted)).connect()

Exception has occurred: sqlalchemy.exc.InterfaceError (ibm_db_dbi.InterfaceError) ibm_db_dbi::InterfaceError: connect expects the first five arguments to be of type string or unicode (Background on this error at: http://sqlalche.me/e/rvf5) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 43, in 

quoted = urllib.quote_plus(CONNECTION_STRING)
create_engine('ibm_db:///?odbc_connect={}'.format(quoted)).connect()

Exception has occurred: sqlalchemy.exc.NoSuchModuleError Cant load plugin: sqlalchemy.dialects:ibm_db

quoted = urllib.quote_plus(CONNECTION_STRING)
create_engine('db2:///?odbc_connect={}'.format(quoted)).connect()

Exception has occurred: sqlalchemy.exc.InterfaceError (ibm_db_dbi.InterfaceError) ibm_db_dbi::InterfaceError: connect expects the first five arguments to be of type string or unicode (Background on this error at: http://sqlalche.me/e/rvf5) File "C:\Git\dashboards\web_app\pandas db2 test.py", line 45, in 

quoted = urllib.quote_plus(CONNECTION_STRING)
create_engine('db2+ibm_db:///?odbc_connect={}'.format(quoted)).connect()

Exception has occurred: sqlalchemy.exc.InterfaceError (ibm_db_dbi.InterfaceError) ibm_db_dbi::InterfaceError: connect expects the first five arguments to be of type string or unicode (Background on this error at: http://sqlalche.me/e/rvf5)

quoted = urllib.quote_plus(CONNECTION_STRING)
create_engine('db2+ibm_db_sa:///?odbc_connect={}'.format(quoted)).connect()

Exception has occurred: sqlalchemy.exc.NoSuchModuleError Cant load plugin: sqlalchemy.dialects:db2.ibm_db_sa

Stacked answered 17/1, 2019 at 17:45 Comment(0)
S
4

I finally got it working, though it's a bit awkward. I created a blank file in my project to appease this message that I was receiving in response to one of the attempts shown in my question:

Unable to open 'hashtable_class_helper.pxi': File not found (file:///c:/git/dashboards/pandas/_libs/hashtable_class_helper.pxi).

(My project folder is C:/Git/dashboards, so I created the rest of the path.)

With that file present, the code below now works for me. engine.connect() works, but I ran an actual query for further verification that it was working. For the record, it seems to work regardless of whether the ibm_db_sa module is modified as suggested in one of the links in my question, so I would recommend leaving that module alone. Note that although they aren't imported directly, you need these modules installed: pyodbc, ibm_db_sa, and possibly future (I forget).

import urllib
import pandas as pd
from sqlalchemy import create_engine

CONNECTION_STRING = (
    "driver={iSeries Access ODBC Driver};"
    "system=ip_address;"
    "database=database_name;"
    "uid=username;"
    "pwd=password;"
)

SQL= """\
SELECT
    MPBASE AS BASEPA,
    COALESCE(SUM(MPQTY), 0) AS PWIP
FROM FUTMODS.MPPROD
WHERE MPOPT <> '*'
GROUP BY MPBASE
"""

quoted = urllib.quote_plus(CONNECTION_STRING)
engine = create_engine('ibm_db_sa+pyodbc:///?odbc_connect={}'.format(quoted))

df = pd.read_sql_query(
    SQL,
    engine,
    index_col='basepa'
)
print df
Stacked answered 17/1, 2019 at 18:38 Comment(0)

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