python - 如何使用 SQLAlchemy 访问 AS/400？

Question

简短版本: 请告诉我如何通过 SQLAlchemy 连接到 AS/400。

长版

我的最终目标是连接来自 SQL Server 和 AS/400 的数据以在 Flask Python 应用程序中显示。我的方法是将每个数据库中的数据获取到 Pandas 数据帧中，然后可以将其连接并输出为 JSON。如果有人有更好的方法，请随时发表评论。我尝试执行此操作的方式的问题是 Pandas.read_sql_query() 依赖于 SQLAlchemy，并且事实证明让 SQLAlchemy 与 AS/400 一起使用非常困难。

• AS/400 是版本 7.2，尽管我可能会尝试连接的另一个版本是版本 5.1。
• 我正在尝试从我的计算机访问它，该计算机运行 Windows 7，并具有 Access 7.1、Python 2.7 和 Python 模块，包括 pyodbc 和 ibm_db_sa。

没有sqlalchemy，pyodbc工作得很好:

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.

我阅读了这些资源以及其他资源，并尝试应用他们的技术:

• https://pypi.org/project/ibm_db_sa/
• Connecting to IBM AS400 server for database operations hangs
• SqlAlchemy equivalent of pyodbc connect string using FreeTDS

下面是我收集的一些失败的尝试和相应的错误消息。我不知道第一部分要放什么(“something+something//...”)，要指定哪个端口(446？8471？其他什么？什么都没有？)，是否要使用服务器的名称或 IP 地址，或者是否使用 create_engine() 的连接字符串样式参数，所以我一直在尝试我能想到的每种组合。我尝试按照上面第二个链接中的建议修改 AS400Dialect_pyodbc 类，之后我尝试再次重新运行一些失败的尝试。我可能会继续尝试，但此时我只是在原地踏步。

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

Answer 1

我终于让它工作了，虽然有点尴尬。我在项目中创建了一个空白文件，以平息我收到的这条消息，以响应我的问题中显示的其中一次尝试:

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

(我的项目文件夹是 C:/Git/dashboards ，所以我创建了路径的其余部分。)

有了该文件，下面的代码现在对我有用。 engine.connect()有效，但我运行了一个实际查询以进一步验证它是否有效。根据记录，无论 ibm_db_sa 是否有效，它似乎都有效。模块已按照我的问题中的链接之一的建议进行修改，因此我建议保留该模块。请注意，虽然它们不是直接导入的，但您需要安装这些模块:pyodbc , ibm_db_sa ，并且可能future (我忘了)。

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