SelectBase no longer a FromClause

As part of the SQLAlchemy 2.0 migration project, a conceptual change has
been made to the role of the :class:`.SelectBase` class hierarchy,
which is the root of all "SELECT" statement constructs, in that they no
longer serve directly as FROM clauses, that is, they no longer subclass
:class:`.FromClause`.  For end users, the change mostly means that any
placement of a :func:`.select` construct in the FROM clause of another
:func:`.select` requires first that it be wrapped in a subquery first,
which historically is through the use of the :meth:`.SelectBase.alias`
method, and is now also available through the use of
:meth:`.SelectBase.subquery`.    This was usually a requirement in any
case since several databases don't accept unnamed SELECT subqueries
in their FROM clause in any case.

See the documentation in this change for lots more detail.

Fixes: #4617
Change-Id: I0f6174ee24b9a1a4529168e52e855e12abd60667

1 files changed, 17 insertions, 15 deletions

diff --git a/test/sql/test_functions.py b/test/sql/test_functions.py
index d2cf1d50a..e0efb1008 100644
--- a/test/sql/test_functions.py
+++ b/test/sql/test_functions.py
@@ -92,7 +92,7 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
                 dialect=dialect,
             )
 
-            functions._registry['_default'].pop('fake_func')
+            functions._registry["_default"].pop("fake_func")
 
     def test_use_labels(self):
         self.assert_compile(
@@ -238,7 +238,7 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
     def test_replace_function(self):
         class replaceable_func(GenericFunction):
             type = Integer
-            identifier = 'replaceable_func'
+            identifier = "replaceable_func"
 
         assert isinstance(func.Replaceable_Func().type, Integer)
         assert isinstance(func.RePlAcEaBlE_fUnC().type, Integer)
@@ -247,11 +247,12 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
         with expect_warnings(
             "The GenericFunction 'replaceable_func' is already registered and "
             "is going to be overriden.",
-            regex=False
+            regex=False,
         ):
+
             class replaceable_func_override(GenericFunction):
                 type = DateTime
-                identifier = 'replaceable_func'
+                identifier = "replaceable_func"
 
         assert isinstance(func.Replaceable_Func().type, DateTime)
         assert isinstance(func.RePlAcEaBlE_fUnC().type, DateTime)
@@ -260,7 +261,7 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
     def test_replace_function_case_insensitive(self):
         class replaceable_func(GenericFunction):
             type = Integer
-            identifier = 'replaceable_func'
+            identifier = "replaceable_func"
 
         assert isinstance(func.Replaceable_Func().type, Integer)
         assert isinstance(func.RePlAcEaBlE_fUnC().type, Integer)
@@ -269,11 +270,12 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
         with expect_warnings(
             "The GenericFunction 'replaceable_func' is already registered and "
             "is going to be overriden.",
-            regex=False
+            regex=False,
         ):
+
             class replaceable_func_override(GenericFunction):
                 type = DateTime
-                identifier = 'REPLACEABLE_Func'
+                identifier = "REPLACEABLE_Func"
 
         assert isinstance(func.Replaceable_Func().type, DateTime)
         assert isinstance(func.RePlAcEaBlE_fUnC().type, DateTime)
@@ -458,14 +460,14 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
             from_obj=[
                 func.calculate(bindparam("x", None), bindparam("y", None))
             ],
-        )
+        ).subquery()
 
         self.assert_compile(
             select([users], users.c.id > calculate.c.z),
             "SELECT users.id, users.name, users.fullname "
             "FROM users, (SELECT q, z, r "
-            "FROM calculate(:x, :y)) "
-            "WHERE users.id > z",
+            "FROM calculate(:x, :y)) AS anon_1 "
+            "WHERE users.id > anon_1.z",
         )
 
         s = select(
@@ -504,8 +506,8 @@ class CompileTest(fixtures.TestBase, AssertsCompiledSQL):
     def test_select_method_two(self):
         expr = func.rows("foo")
         self.assert_compile(
-            select(["*"]).select_from(expr.select()),
-            "SELECT * FROM (SELECT rows(:rows_2) AS rows_1)",
+            select(["*"]).select_from(expr.select().subquery()),
+            "SELECT * FROM (SELECT rows(:rows_2) AS rows_1) AS anon_1",
         )
 
     def test_select_method_three(self):
@@ -1087,7 +1089,7 @@ class RegisterTest(fixtures.TestBase, AssertsCompiledSQL):
         functions._registry = self._registry
 
     def test_GenericFunction_is_registered(self):
-        assert 'GenericFunction' not in functions._registry['_default']
+        assert "GenericFunction" not in functions._registry["_default"]
 
     def test_register_function(self):
 
@@ -1101,7 +1103,7 @@ class RegisterTest(fixtures.TestBase, AssertsCompiledSQL):
         class registered_func_child(registered_func):
             type = sqltypes.Integer
 
-        assert 'registered_func' in functions._registry['_default']
+        assert "registered_func" in functions._registry["_default"]
         assert isinstance(func.registered_func_child().type, Integer)
 
         class not_registered_func(GenericFunction):
@@ -1113,5 +1115,5 @@ class RegisterTest(fixtures.TestBase, AssertsCompiledSQL):
         class not_registered_func_child(not_registered_func):
             type = sqltypes.Integer
 
-        assert 'not_registered_func' not in functions._registry['_default']
+        assert "not_registered_func" not in functions._registry["_default"]
         assert isinstance(func.not_registered_func_child().type, Integer)