When querying the information schema on SQL Server 2000, removed

a CAST call that was added in 0.8.1 to help with driver issues,
which apparently is not compatible on 2000.
The CAST remains in place for SQL Server 2005 and greater.
[ticket:2747]

4 files changed, 58 insertions, 4 deletions

diff --git a/doc/build/changelog/changelog_08.rst b/doc/build/changelog/changelog_08.rst
index 82e65272b..e3b14bc28 100644
--- a/doc/build/changelog/changelog_08.rst
+++ b/doc/build/changelog/changelog_08.rst
@@ -7,6 +7,15 @@
     :version: 0.8.2
 
     .. change::
+        :tags: bug, mssql
+        :tickets: 2747
+
+        When querying the information schema on SQL Server 2000, removed
+        a CAST call that was added in 0.8.1 to help with driver issues,
+        which apparently is not compatible on 2000.
+        The CAST remains in place for SQL Server 2005 and greater.
+
+    .. change::
         :tags: bug, mysql
         :tickets: 2721
 
diff --git a/doc/build/changelog/changelog_09.rst b/doc/build/changelog/changelog_09.rst
index c5ee84a7b..1c27d7bf6 100644
--- a/doc/build/changelog/changelog_09.rst
+++ b/doc/build/changelog/changelog_09.rst
@@ -7,6 +7,16 @@
     :version: 0.9.0
 
     .. change::
+        :tags: bug, mssql
+        :tickets: 2747
+
+        When querying the information schema on SQL Server 2000, removed
+        a CAST call that was added in 0.8.1 to help with driver issues,
+        which apparently is not compatible on 2000.
+        The CAST remains in place for SQL Server 2005 and greater.
+        Also in 0.8.2.
+
+    .. change::
         :tags: bug, mysql
         :tickets: 2721
 
diff --git a/lib/sqlalchemy/dialects/mssql/information_schema.py b/lib/sqlalchemy/dialects/mssql/information_schema.py
index a7628f213..c0d5d9168 100644
--- a/lib/sqlalchemy/dialects/mssql/information_schema.py
+++ b/lib/sqlalchemy/dialects/mssql/information_schema.py
@@ -10,10 +10,11 @@ from ... import Table, MetaData, Column
 from ...types import String, Unicode, Integer, TypeDecorator
 from ... import cast
 from ... import util
+from ...sql import expression
+from ...ext.compiler import compiles
 
 ischema = MetaData()
 
-
 class CoerceUnicode(TypeDecorator):
     impl = Unicode
 
@@ -23,7 +24,19 @@ class CoerceUnicode(TypeDecorator):
         return value
 
     def bind_expression(self, bindvalue):
-        return cast(bindvalue, Unicode)
+        return _cast_on_2005(bindvalue)
+
+class _cast_on_2005(expression.ColumnElement):
+    def __init__(self, bindvalue):
+        self.bindvalue = bindvalue
+
+@compiles(_cast_on_2005)
+def _compile(element, compiler, **kw):
+    from . import base
+    if compiler.dialect.server_version_info < base.MS_2005_VERSION:
+        return compiler.process(element.bindvalue, **kw)
+    else:
+        return compiler.process(cast(element.bindvalue, Unicode), **kw)
 
 schemata = Table("SCHEMATA", ischema,
     Column("CATALOG_NAME", CoerceUnicode, key="catalog_name"),
diff --git a/test/dialect/test_mssql.py b/test/dialect/test_mssql.py
index 4a99ef5f7..b2eb8609b 100644
--- a/test/dialect/test_mssql.py
+++ b/test/dialect/test_mssql.py
@@ -2078,14 +2078,36 @@ class BinaryTest(fixtures.TestBase, AssertsExecutionResults):
         fp.close()
         return stream
 
-class InfoCoerceUnicodeTest(fixtures.TestBase):
+from sqlalchemy.dialects.mssql.information_schema import CoerceUnicode, tables
+from sqlalchemy.dialects.mssql import base
+
+class InfoCoerceUnicodeTest(fixtures.TestBase, AssertsCompiledSQL):
     def test_info_unicode_coercion(self):
-        from sqlalchemy.dialects.mssql.information_schema import CoerceUnicode
 
         dialect = mssql.dialect()
         value = CoerceUnicode().bind_processor(dialect)('a string')
         assert isinstance(value, util.text_type)
 
+    def test_info_unicode_cast_no_2000(self):
+        dialect = mssql.dialect()
+        dialect.server_version_info = base.MS_2000_VERSION
+        stmt = tables.c.table_name == 'somename'
+        self.assert_compile(
+            stmt,
+            "[TABLES_1].[TABLE_NAME] = :TABLE_NAME_1",
+            dialect=dialect
+        )
+
+    def test_info_unicode_cast(self):
+        dialect = mssql.dialect()
+        dialect.server_version_info = base.MS_2005_VERSION
+        stmt = tables.c.table_name == 'somename'
+        self.assert_compile(
+            stmt,
+            "[TABLES_1].[TABLE_NAME] = CAST(:TABLE_NAME_1 AS NVARCHAR(max))",
+            dialect=dialect
+        )
+
 class ReflectHugeViewTest(fixtures.TestBase):
     __only_on__ = 'mssql'