https://github.com/level12/sqlalchemy_pyodbc_mssql
SQLAlchemy dialect for mssql using pyodbc
https://github.com/level12/sqlalchemy_pyodbc_mssql
Last synced: 4 months ago
JSON representation
SQLAlchemy dialect for mssql using pyodbc
- Host: GitHub
- URL: https://github.com/level12/sqlalchemy_pyodbc_mssql
- Owner: level12
- Created: 2019-06-14T18:06:53.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2022-10-24T19:44:54.000Z (over 2 years ago)
- Last Synced: 2024-04-16T02:13:09.173Z (12 months ago)
- Language: Python
- Size: 8.79 KB
- Stars: 18
- Watchers: 4
- Forks: 2
- Open Issues: 3
-
Metadata Files:
- Readme: readme.rst
- Changelog: changelog.rst
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- jimsghstars - level12/sqlalchemy_pyodbc_mssql - SQLAlchemy dialect for mssql using pyodbc (Python)
README
sqlalchemy_pyodbc_mssql Readme
==========================================
.. image:: https://circleci.com/gh/level12/sqlalchemy_pyodbc_mssql.svg?&style=shield
:target: https://circleci.com/gh/level12/sqlalchemy_pyodbc_mssql
.. image:: https://codecov.io/gh/level12/sqlalchemy_pyodbc_mssql/branch/master/graph/badge.svg
:target: https://codecov.io/github/level12/sqlalchemy_pyodbc_mssql?branch=master
Overview
--------
PyODBC is Microsoft's recommended DBAPI layer for connecting a python application to MSSQL. However,
the layer is not MSSQL-specific, and so it has some limitations:
- parameterized queries with GROUP BY will not always work ([source](https://github.com/mkleehammer/pyodbc/issues/479))
- stored procedures (such as those called by the prepared statements in pyodbc) are limited to
2100 parameters ([source](https://docs.microsoft.com/en-us/sql/sql-server/maximum-capacity-specifications-for-sql-server?view=sql-server-2017))
SQLAlchemy has a PyODBC dialect for MSSQL usage, but it also shares these limitations.
- for GROUP BY details, see https://github.com/sqlalchemy/sqlalchemy/issues/4540
[PyMSSQL](http://www.pymssql.org) exists as an alternative DBAPI layer and dialect for SQLAlchemy. Since it prepares queries
by rolling parameters into the query string itself (properly quoted, of course) rather than issuing
ODBC prepared statements, it does not share the above problems.
sqlalchemy_pyodbc_mssql extends the built-in SQLAlchemy PyODBC dialect in order to work around
these limits in a manner consistent with PyMSSQL's implementation. Most queries are passed as-is to
PyODBC to be prepared and executed normally. Those that would not work, due to the above issues,
are given special treatment to avoid the limitations and keep the app developer from needing to
keep track of when to apply workarounds.
Usage
-----
- Installation
- for usage in app: `pip install sqlalchemy_pyodbc_mssql`
- to run tests: `pip install sqlalchemy_pyodbc_mssql[tests]`
- Usage
- see [SQLAlchemy instructions for PyODBC usage](https://docs.sqlalchemy.org/en/13/dialects/mssql.html#module-sqlalchemy.dialects.mssql.pyodbc)
- dialect name to use is `mssql+pyodbc_mssql`
- examples:
- `mssql+pyodbc_mssql://:@`
- `mssql+pyodbc_mssql://:@?driver=SQL+Server+Native+Client+11.0`