- Fixed a regression that was incorrectly fixed in 1.0.0b4

(hence becoming two regressions); reports that
SELECT statements would GROUP BY a label name and fail was misconstrued
that certain backends such as SQL Server should not be emitting
ORDER BY or GROUP BY on a simple label name at all; when in fact,
we had forgotten that 0.9 was already emitting ORDER BY on a simple
label name for all backends, as described in :ref:`migration_1068`,
as 1.0 had rewritten this logic as part of :ticket:`2992`.

In 1.0.2, the bug is fixed both that SQL Server, Firebird and others
will again emit ORDER BY on a simple label name when passed a
:class:`.Label` construct that is expressed in the columns clause,
and no backend will emit GROUP BY on a simple label name in this case,
as even Postgresql can't reliably do GROUP BY on a simple name
in every case.
fixes #3338, fixes #3385

7 files changed, 47 insertions, 7 deletions

diff --git a/doc/build/changelog/changelog_10.rst b/doc/build/changelog/changelog_10.rst
index 319e58b78..5c98accef 100644
--- a/doc/build/changelog/changelog_10.rst
+++ b/doc/build/changelog/changelog_10.rst
@@ -19,6 +19,26 @@
     :version: 1.0.2
 
     .. change::
+        :tags: bug, sql
+        :tickets: 3338, 3385
+
+        Fixed a regression that was incorrectly fixed in 1.0.0b4
+        (hence becoming two regressions); reports that
+        SELECT statements would GROUP BY a label name and fail was misconstrued
+        that certain backends such as SQL Server should not be emitting
+        ORDER BY or GROUP BY on a simple label name at all; when in fact,
+        we had forgotten that 0.9 was already emitting ORDER BY on a simple
+        label name for all backends, as described in :ref:`migration_1068`,
+        as 1.0 had rewritten this logic as part of :ticket:`2992`.
+
+        In 1.0.2, the bug is fixed both that SQL Server, Firebird and others
+        will again emit ORDER BY on a simple label name when passed a
+        :class:`.Label` construct that is expressed in the columns clause,
+        and no backend will emit GROUP BY on a simple label name in this case,
+        as even Postgresql can't reliably do GROUP BY on a simple name
+        in every case.
+
+    .. change::
         :tags: bug, ext, declarative
         :tickets: 3383
 
diff --git a/lib/sqlalchemy/dialects/firebird/base.py b/lib/sqlalchemy/dialects/firebird/base.py
index e407e2f25..c34829cd3 100644
--- a/lib/sqlalchemy/dialects/firebird/base.py
+++ b/lib/sqlalchemy/dialects/firebird/base.py
@@ -394,8 +394,6 @@ class FBDialect(default.DefaultDialect):
     requires_name_normalize = True
     supports_empty_insert = False
 
-    supports_simple_order_by_label = False
-
     statement_compiler = FBCompiler
     ddl_compiler = FBDDLCompiler
     preparer = FBIdentifierPreparer
diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py
index 522e59b00..b073af6af 100644
--- a/lib/sqlalchemy/dialects/mssql/base.py
+++ b/lib/sqlalchemy/dialects/mssql/base.py
@@ -1417,7 +1417,6 @@ class MSDialect(default.DefaultDialect):
     use_scope_identity = True
     max_identifier_length = 128
     schema_name = "dbo"
-    supports_simple_order_by_label = False
 
     colspecs = {
         sqltypes.DateTime: _MSDateTime,
diff --git a/lib/sqlalchemy/dialects/sybase/base.py b/lib/sqlalchemy/dialects/sybase/base.py
index 1baab6db4..ae0473a3e 100644
--- a/lib/sqlalchemy/dialects/sybase/base.py
+++ b/lib/sqlalchemy/dialects/sybase/base.py
@@ -435,7 +435,6 @@ class SybaseDialect(default.DefaultDialect):
     supports_native_boolean = False
     supports_unicode_binds = False
     postfetch_lastrowid = True
-    supports_simple_order_by_label = False
 
     colspecs = {}
     ischema_names = ischema_names
diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index 6ee4053a7..a178ed99a 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -3724,6 +3724,16 @@ def _literal_as_label_reference(element):
     elif hasattr(element, '__clause_element__'):
         element = element.__clause_element__()
 
+    return _literal_as_text(element)
+
+
+def _literal_and_labels_as_label_reference(element):
+    if isinstance(element, util.string_types):
+        return _textual_label_reference(element)
+
+    elif hasattr(element, '__clause_element__'):
+        element = element.__clause_element__()
+
     if isinstance(element, ColumnElement) and \
             element._order_by_label_element is not None:
         return _label_reference(element)
diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index 7d8c885ae..245c54817 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -16,7 +16,7 @@ from .elements import _clone, \
     _literal_as_text, _interpret_as_column_or_from, _expand_cloned,\
     _select_iterables, _anonymous_label, _clause_element_as_expr,\
     _cloned_intersection, _cloned_difference, True_, \
-    _literal_as_label_reference
+    _literal_as_label_reference, _literal_and_labels_as_label_reference
 from .base import Immutable, Executable, _generative, \
     ColumnCollection, ColumnSet, _from_objects, Generative
 from . import type_api
@@ -1723,7 +1723,7 @@ class GenerativeSelect(SelectBase):
         if order_by is not None:
             self._order_by_clause = ClauseList(
                 *util.to_list(order_by),
-                _literal_as_text=_literal_as_label_reference)
+                _literal_as_text=_literal_and_labels_as_label_reference)
         if group_by is not None:
             self._group_by_clause = ClauseList(
                 *util.to_list(group_by),
@@ -1912,7 +1912,8 @@ class GenerativeSelect(SelectBase):
             if getattr(self, '_order_by_clause', None) is not None:
                 clauses = list(self._order_by_clause) + list(clauses)
             self._order_by_clause = ClauseList(
-                *clauses, _literal_as_text=_literal_as_label_reference)
+                *clauses,
+                _literal_as_text=_literal_and_labels_as_label_reference)
 
     def append_group_by(self, *clauses):
         """Append the given GROUP BY criterion applied to this selectable.
diff --git a/test/sql/test_compiler.py b/test/sql/test_compiler.py
index 03646d78d..04e3171a9 100644
--- a/test/sql/test_compiler.py
+++ b/test/sql/test_compiler.py
@@ -961,6 +961,19 @@ class SelectTest(fixtures.TestBase, AssertsCompiledSQL):
             dialect=dialect
         )
 
+    def test_no_group_by_labels(self):
+        lab1 = (table1.c.myid + 12).label('foo')
+        lab2 = func.somefunc(table1.c.name).label('bar')
+        dialect = default.DefaultDialect()
+
+        self.assert_compile(
+            select([lab1, lab2]).group_by(lab1, lab2),
+            "SELECT mytable.myid + :myid_1 AS foo, somefunc(mytable.name) "
+            "AS bar FROM mytable GROUP BY mytable.myid + :myid_1, "
+            "somefunc(mytable.name)",
+            dialect=dialect
+        )
+
     def test_conjunctions(self):
         a, b, c = text('a'), text('b'), text('c')
         x = and_(a, b, c)