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| author | Mike Bayer <mike_mp@zzzcomputing.com> | 2019-06-13 12:37:22 -0400 |
|---|---|---|
| committer | Mike Bayer <mike_mp@zzzcomputing.com> | 2019-07-06 13:02:22 -0400 |
| commit | ef7ff058eb67d73ebeac7b125ab2a7806e14629c (patch) | |
| tree | 9a09162961f7bcdb6d16837adacabb99f10b4410 /lib/sqlalchemy/engine | |
| parent | 1ce98ca83a4b2da12e52aa0f4ab181c83063abc2 (diff) | |
| download | sqlalchemy-ef7ff058eb67d73ebeac7b125ab2a7806e14629c.tar.gz | |
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
Diffstat (limited to 'lib/sqlalchemy/engine')
| -rw-r--r-- | lib/sqlalchemy/engine/result.py | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py index 740565f5e..480d086ff 100644 --- a/lib/sqlalchemy/engine/result.py +++ b/lib/sqlalchemy/engine/result.py @@ -300,7 +300,7 @@ class ResultMetaData(object): # if we did a pure positional match, then reset the # original "expression element" back to the "unambiguous" # entry. This is a new behavior in 1.1 which impacts - # TextAsFrom but also straight compiled SQL constructs. + # TextualSelect but also straight compiled SQL constructs. if not self.matched_on_name: self._keymap.update( [ @@ -363,7 +363,7 @@ class ResultMetaData(object): The remaining fairly common case is that of the textual SQL that includes at least partial column information; this is when - we use a :class:`.TextAsFrom` construct. This construct may have + we use a :class:`.TextualSelect` construct. This construct may have unordered or ordered column information. In the ordered case, we merge the cursor.description and the compiled construct's information positionally, and warn if there are additional description names @@ -386,7 +386,7 @@ class ResultMetaData(object): SQLAlchemy for all cases up through te 0.9 series. Positional matching for compiled SQL expressions was introduced in 1.0 as a major performance feature, and positional matching for textual - :class:`.TextAsFrom` objects in 1.1. As name matching is no longer + :class:`.TextualSelect` objects in 1.1. As name matching is no longer a common case, it was acceptable to factor it into smaller generator- oriented methods that are easier to understand, but incur slightly more performance overhead. |