Added new attribute :attr:`_sql.Select.columns_clause_froms` that will
retrieve the FROM list implied by the columns clause of the
:class:`_sql.Select` statement. This differs from the old
:attr:`_sql.Select.froms` collection in that it does not perform any ORM
compilation steps, which necessarily deannotate the FROM elements and do
things like compute joinedloads etc., which makes it not an appropriate
candidate for the :meth:`_sql.Select.select_from` method. Additionally adds
a new parameter
:paramref:`_sql.Select.with_only_columns.maintain_column_froms` that
transfers this collection to :meth:`_sql.Select.select_from` before
replacing the columns collection.

In addition, the :attr:`_sql.Select.froms` is renamed to
:meth:`_sql.Select.get_final_froms`, to stress that this collection is not
a simple accessor and is instead calculated given the full state of the
object, which can be an expensive call when used in an ORM context.

Additionally fixes a regression involving the
:func:`_orm.with_only_columns` function to support applying criteria to
column elements that were replaced with either
:meth:`_sql.Select.with_only_columns` or :meth:`_orm.Query.with_entities` ,
which had broken as part of :ticket:`6503` released in 1.4.19.

Fixes: #6808

Change-Id: Ib5d66cce488bbaca06dab4f68fb5cdaa73e8823e

Change-Id: I04057cc3d3f93de60b02999803e2ba6a23cdf68d

Fixed issue where use of the :paramref:`_sql.case.whens` parameter passing
a dictionary positionally and not as a keyword argument would emit a 2.0
deprecation warning, referring to the deprecation of passing a list
positionally. The dictionary format of "whens", passed positionally, is
still supported and was accidentally marked as deprecated.

Removes warning filter for case statement.

Fixes: #6786
Change-Id: I8efd1882563773bec89ae5e34f0dfede77fc4683

Change-Id: I488c9557eda390e4a88319affd4c8813ee274f80

Fixed regression caused by the "empty in" change just made in
:ticket:`6397` 1.4.12 where the expression needs to be parenthesized for
the "not in" use case, otherwise the condition will interfere with the
other filtering criteria.

also amends StrSQLCompiler to use the newer "empty IN" style for
its compilation process.

Fixes: #6428
Change-Id: I182a552fc0d3065a9e38c0f4ece2deb143735c36

Established a deprecation path for calling upon the
:meth:`_cursor.CursorResult.keys` method for a statement that returns no
rows to provide support for legacy patterns used by the "records" package
as well as any other non-migrated applications. Previously, this would
raise :class:`.ResourceClosedException` unconditionally in the same way as
it does when attempting to fetch rows. While this is the correct behavior
going forward, the :class:`_cursor.LegacyCursorResult` object will now in
this case return an empty list for ``.keys()`` as it did in 1.3, while also
emitting a 2.0 deprecation warning. The :class:`_cursor.CursorResult`, used
when using a 2.0-style "future" engine, will continue to raise as it does
now.

Fixes: #6427
Change-Id: I4148f28c88039e4141deeab28b1a5994e6d6e098

Fixed an issue with the (deprecated in 1.4)
:meth:`_schema.ForeignKeyConstraint.copy` method that caused an error when
invoked with the ``schema`` argument.

Fixes: #6353
Change-Id: I03330d9ec254d64377f2b2e86af69a4eaff43ac6

Fixed regression where use of an arbitrary iterable with the
:func:`_sql.select` function was not working, outside of plain lists. The
forwards/backwards compatibility logic here now checks for a wider range of
incoming "iterable" types including that a ``.c`` collection from a
selectable can be passed directly. Pull request compliments of Oliver Rice.

Fixes: #5935
Closes: #5936
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5936
Pull-request-sha: 575ab3e7df30fc8da03752d102c8eeb6cb3a3e3d

Change-Id: Icd972f1078d9ea96c47a64133079f00d9b0a66f3