CAST bind values against SQL Server sys into NVARCHAR

Ensured that the queries used to reflect indexes and view definitions will
explicitly CAST string parameters into NVARCHAR, as many SQL Server drivers
frequently treat string values, particularly those with non-ascii
characters or larger string values, as TEXT which often don't compare
correctly against VARCHAR characters in SQL Server's information schema
tables for some reason.    These CAST operations already take place for
reflection queries against SQL Server ``information_schema.`` tables but
were missing from three additional queries that are against ``sys.``
tables.

Fixes: #4745
Change-Id: I3056533bf1a1e8ef17742879d369ab13f8b704ea

3 files changed, 36 insertions, 6 deletions

diff --git a/doc/build/changelog/unreleased_13/4745.rst b/doc/build/changelog/unreleased_13/4745.rst
new file mode 100644
index 000000000..0728588a1
--- /dev/null
+++ b/doc/build/changelog/unreleased_13/4745.rst
@@ -0,0 +1,13 @@
+.. change::
+    :tags: bug, mssql
+    :tickets: 4745
+
+    Ensured that the queries used to reflect indexes and view definitions will
+    explicitly CAST string parameters into NVARCHAR, as many SQL Server drivers
+    frequently treat string values, particularly those with non-ascii
+    characters or larger string values, as TEXT which often don't compare
+    correctly against VARCHAR characters in SQL Server's information schema
+    tables for some reason.    These CAST operations already take place for
+    reflection queries against SQL Server ``information_schema.`` tables but
+    were missing from three additional queries that are against ``sys.``
+    tables.
diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py
index 99abba2c6..b2bcc280c 100644
--- a/lib/sqlalchemy/dialects/mssql/base.py
+++ b/lib/sqlalchemy/dialects/mssql/base.py
@@ -2426,8 +2426,8 @@ class MSDialect(default.DefaultDialect):
                 "and ind.is_primary_key=0 and ind.type != 0"
             )
             .bindparams(
-                sql.bindparam("tabname", tablename, sqltypes.String()),
-                sql.bindparam("schname", owner, sqltypes.String()),
+                sql.bindparam("tabname", tablename, ischema.CoerceUnicode()),
+                sql.bindparam("schname", owner, ischema.CoerceUnicode()),
             )
             .columns(name=sqltypes.Unicode())
         )
@@ -2451,8 +2451,8 @@ class MSDialect(default.DefaultDialect):
                 "and sch.name=:schname"
             )
             .bindparams(
-                sql.bindparam("tabname", tablename, sqltypes.String()),
-                sql.bindparam("schname", owner, sqltypes.String()),
+                sql.bindparam("tabname", tablename, ischema.CoerceUnicode()),
+                sql.bindparam("schname", owner, ischema.CoerceUnicode()),
             )
             .columns(name=sqltypes.Unicode())
         )
@@ -2477,8 +2477,8 @@ class MSDialect(default.DefaultDialect):
                 "views.schema_id=sch.schema_id and "
                 "views.name=:viewname and sch.name=:schname"
             ).bindparams(
-                sql.bindparam("viewname", viewname, sqltypes.String()),
-                sql.bindparam("schname", owner, sqltypes.String()),
+                sql.bindparam("viewname", viewname, ischema.CoerceUnicode()),
+                sql.bindparam("schname", owner, ischema.CoerceUnicode()),
             )
         )
 
diff --git a/test/dialect/mssql/test_reflection.py b/test/dialect/mssql/test_reflection.py
index d9b65d4e0..8393a7b48 100644
--- a/test/dialect/mssql/test_reflection.py
+++ b/test/dialect/mssql/test_reflection.py
@@ -209,6 +209,23 @@ class ReflectionTest(fixtures.TestBase, ComparesTables, AssertsCompiledSQL):
         )
 
     @testing.provide_metadata
+    def test_table_name_that_is_greater_than_16_chars(self):
+        metadata = self.metadata
+        Table(
+            "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
+            metadata,
+            Column("id", Integer, primary_key=True),
+            Column("foo", Integer),
+            Index("foo_idx", "foo"),
+        )
+        metadata.create_all()
+
+        t = Table(
+            "ABCDEFGHIJKLMNOPQRSTUVWXYZ", MetaData(), autoload_with=testing.db
+        )
+        eq_(t.name, "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+    @testing.provide_metadata
     def test_db_qualified_items(self):
         metadata = self.metadata
         Table("foo", metadata, Column("id", Integer, primary_key=True))