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