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139 lines
4.7 KiB
139 lines
4.7 KiB
# mssql/pymssql.py
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# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: https://www.opensource.org/licenses/mit-license.php
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"""
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.. dialect:: mssql+pymssql
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:name: pymssql
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:dbapi: pymssql
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:connectstring: mssql+pymssql://<username>:<password>@<freetds_name>/?charset=utf8
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pymssql is a Python module that provides a Python DBAPI interface around
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`FreeTDS <https://www.freetds.org/>`_.
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.. note::
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pymssql is currently not included in SQLAlchemy's continuous integration
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(CI) testing.
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Modern versions of this driver worked very well with SQL Server and FreeTDS
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from Linux and were highly recommended. However, pymssql is currently
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unmaintained and has fallen behind the progress of the Microsoft ODBC driver in
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its support for newer features of SQL Server. The latest official release of
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pymssql at the time of this document is version 2.1.4 (August, 2018) and it
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lacks support for:
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1. table-valued parameters (TVPs),
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2. ``datetimeoffset`` columns using timezone-aware ``datetime`` objects
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(values are sent and retrieved as strings), and
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3. encrypted connections (e.g., to Azure SQL), when pymssql is installed from
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the pre-built wheels. Support for encrypted connections requires building
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pymssql from source, which can be a nuisance, especially under Windows.
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The above features are all supported by mssql+pyodbc when using Microsoft's
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ODBC Driver for SQL Server (msodbcsql), which is now available for Windows,
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(several flavors of) Linux, and macOS.
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""" # noqa
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import re
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from .base import MSDialect
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from .base import MSIdentifierPreparer
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from ... import processors
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from ... import types as sqltypes
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from ... import util
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class _MSNumeric_pymssql(sqltypes.Numeric):
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def result_processor(self, dialect, type_):
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if not self.asdecimal:
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return processors.to_float
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else:
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return sqltypes.Numeric.result_processor(self, dialect, type_)
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class MSIdentifierPreparer_pymssql(MSIdentifierPreparer):
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def __init__(self, dialect):
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super(MSIdentifierPreparer_pymssql, self).__init__(dialect)
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# pymssql has the very unusual behavior that it uses pyformat
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# yet does not require that percent signs be doubled
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self._double_percents = False
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class MSDialect_pymssql(MSDialect):
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supports_statement_cache = True
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supports_native_decimal = True
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driver = "pymssql"
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preparer = MSIdentifierPreparer_pymssql
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colspecs = util.update_copy(
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MSDialect.colspecs,
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{sqltypes.Numeric: _MSNumeric_pymssql, sqltypes.Float: sqltypes.Float},
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)
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@classmethod
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def dbapi(cls):
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module = __import__("pymssql")
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# pymmsql < 2.1.1 doesn't have a Binary method. we use string
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client_ver = tuple(int(x) for x in module.__version__.split("."))
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if client_ver < (2, 1, 1):
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# TODO: monkeypatching here is less than ideal
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module.Binary = lambda x: x if hasattr(x, "decode") else str(x)
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if client_ver < (1,):
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util.warn(
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"The pymssql dialect expects at least "
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"the 1.0 series of the pymssql DBAPI."
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)
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return module
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def _get_server_version_info(self, connection):
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vers = connection.exec_driver_sql("select @@version").scalar()
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m = re.match(r"Microsoft .*? - (\d+)\.(\d+)\.(\d+)\.(\d+)", vers)
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if m:
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return tuple(int(x) for x in m.group(1, 2, 3, 4))
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else:
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return None
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def create_connect_args(self, url):
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opts = url.translate_connect_args(username="user")
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opts.update(url.query)
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port = opts.pop("port", None)
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if port and "host" in opts:
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opts["host"] = "%s:%s" % (opts["host"], port)
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return [[], opts]
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def is_disconnect(self, e, connection, cursor):
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for msg in (
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"Adaptive Server connection timed out",
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"Net-Lib error during Connection reset by peer",
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"message 20003", # connection timeout
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"Error 10054",
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"Not connected to any MS SQL server",
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"Connection is closed",
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"message 20006", # Write to the server failed
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"message 20017", # Unexpected EOF from the server
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"message 20047", # DBPROCESS is dead or not enabled
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):
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if msg in str(e):
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return True
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else:
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return False
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def set_isolation_level(self, connection, level):
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if level == "AUTOCOMMIT":
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connection.autocommit(True)
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else:
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connection.autocommit(False)
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super(MSDialect_pymssql, self).set_isolation_level(
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connection, level
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)
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dialect = MSDialect_pymssql
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