class NamedColumn(KeyedColumnElement[
Known subclasses: sqlalchemy.sql.elements.ColumnClause
, sqlalchemy.sql.elements.Label
, sqlalchemy.sql.elements.TableValuedColumn
, sqlalchemy.sql.functions.ScalarFunctionColumn
Undocumented
Class Variable | is |
Undocumented |
Class Variable | key |
The 'key' that in some circumstances refers to this object in a Python namespace. |
Class Variable | name |
Undocumented |
Class Variable | table |
Undocumented |
Property | description |
Undocumented |
Method | _bind |
Undocumented |
Method | _compare |
Return True if the given column element compares to this one when targeting within a result row. |
Method | _gen |
Undocumented |
Method | _make |
Create a new :class:`_expression.ColumnElement` representing this :class:`_expression.ColumnElement` as it appears in the select list of a descending selectable. |
Method | _non |
the 'name' that naturally applies this element when rendered in SQL. |
Method | _render |
A flag used by select._columns_plus_names that helps to determine we are actually going to render in terms of "SELECT <col> AS <label>". This flag can be returned as False for some Column objects that want to be rendered as simple "SELECT <col>"; typically columns that don't have any parent table and are named the same as what the label would be in any case. |
Method | _tq |
table qualified label based on column key. |
Method | _tq |
table qualified label based on column name. |
Inherited from KeyedColumnElement
:
Class Variable | _is |
Undocumented |
Inherited from ColumnElement
(via KeyedColumnElement
):
Method | __getattr__ |
Undocumented |
Method | cast |
Produce a type cast, i.e. ``CAST(<expression> AS <type>)``. |
Method | comparator |
Undocumented |
Method | label |
Produce a column label, i.e. ``<columnname> AS <name>``. |
Method | operate |
Operate on an argument. |
Method | reverse |
Reverse operate on an argument. |
Method | self |
Apply a 'grouping' to this :class:`_expression.ClauseElement`. |
Method | shares |
Return True if the given :class:`_expression.ColumnElement` has a common ancestor to this :class:`_expression.ColumnElement`. |
Class Variable | __visit |
Undocumented |
Class Variable | foreign |
Undocumented |
Class Variable | primary |
Undocumented |
Property | anon |
Undocumented |
Property | anon |
Undocumented |
Property | base |
Undocumented |
Property | expression |
Return a column expression. |
Property | proxy |
set of all columns we are proxying |
Property | type |
Undocumented |
Method | _anon |
Undocumented |
Method | _dedupe |
label to apply to a column that is anon labeled, but repeated in the SELECT, so that we have to make an "extra anon" label that disambiguates it from the previous appearance. |
Method | _dedupe |
Undocumented |
Method | _expression |
a suggested label to use in the case that the column has no name, which should be used if possible as the explicit 'AS <label>' where this expression would normally have an anon label. |
Method | _negate |
Undocumented |
Method | _proxy |
Undocumented |
Method | _uncached |
An 'uncached' version of proxy set. |
Class Variable | _allow |
A flag that can be flipped to prevent a column from being resolvable by string label name. |
Class Variable | _alt |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Property | _anon |
Provides a constant 'anonymous key label' for this ColumnElement. |
Property | _anon |
Provides a constant 'anonymous label' for this ColumnElement. |
Property | _anon |
Undocumented |
Property | _anon |
Undocumented |
Property | _expanded |
Undocumented |
Property | _key |
legacy; renamed to _tq_key_label |
Property | _label |
legacy; renamed to _tq_label |
Property | _proxies |
Undocumented |
Property | _select |
Undocumented |
Inherited from ColumnArgumentOrKeyRole
(via KeyedColumnElement
, ColumnElement
):
Class Variable | __slots__ |
Undocumented |
Class Variable | _role |
Undocumented |
Inherited from AllowsLambdaRole
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
):
Class Variable | allows |
Undocumented |
Inherited from UsesInspection
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
):
Class Variable | uses |
Undocumented |
Class Variable | _post |
Undocumented |
Inherited from SQLCoreOperations
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
):
Method | __add__ |
Implement the ``+`` operator. |
Method | __and__ |
Implement the ``&`` operator. |
Method | __contains__ |
Undocumented |
Method | __eq__ |
Implement the ``==`` operator. |
Method | __floordiv__ |
Implement the ``//`` operator. |
Method | __ge__ |
Implement the ``>=`` operator. |
Method | __getitem__ |
Implement the [] operator. |
Method | __gt__ |
Implement the ``>`` operator. |
Method | __invert__ |
Implement the ``~`` operator. |
Method | __le__ |
Implement the ``<=`` operator. |
Method | __lt__ |
Implement the ``<`` operator. |
Method | __mod__ |
Implement the ``%`` operator. |
Method | __mul__ |
Implement the ``*`` operator. |
Method | __ne__ |
Implement the ``!=`` operator. |
Method | __neg__ |
Implement the ``-`` operator. |
Method | __or__ |
Implement the ``|`` operator. |
Method | __radd__ |
Implement the ``+`` operator in reverse. |
Method | __rfloordiv__ |
Implement the ``//`` operator in reverse. |
Method | __rmod__ |
Implement the ``%`` operator in reverse. |
Method | __rmul__ |
Implement the ``*`` operator in reverse. |
Method | __rsub__ |
Implement the ``-`` operator in reverse. |
Method | __rtruediv__ |
Implement the ``/`` operator in reverse. |
Method | __sub__ |
Implement the ``-`` operator. |
Method | __truediv__ |
Implement the ``/`` operator. |
Method | all_ |
Produce an :func:`_expression.all_` clause against the parent object. |
Method | any_ |
Produce an :func:`_expression.any_` clause against the parent object. |
Method | asc |
Produce a :func:`_expression.asc` clause against the parent object. |
Method | between |
Produce a :func:`_expression.between` clause against the parent object, given the lower and upper range. |
Method | bool |
Return a custom boolean operator. |
Method | collate |
Produce a :func:`_expression.collate` clause against the parent object, given the collation string. |
Method | concat |
Implement the 'concat' operator. |
Method | contains |
Implement the 'contains' operator. |
Method | desc |
Produce a :func:`_expression.desc` clause against the parent object. |
Method | distinct |
Produce a :func:`_expression.distinct` clause against the parent object. |
Method | endswith |
Implement the 'endswith' operator. |
Method | ilike |
Implement the ``ilike`` operator, e.g. case insensitive LIKE. |
Method | in_ |
Implement the ``in`` operator. |
Method | is_ |
Implement the ``IS`` operator. |
Method | is |
Implement the ``IS DISTINCT FROM`` operator. |
Method | is |
Implement the ``IS NOT`` operator. |
Method | is |
Implement the ``IS NOT DISTINCT FROM`` operator. |
Method | isnot |
Undocumented |
Method | like |
Implement the ``like`` operator. |
Method | match |
Implements a database-specific 'match' operator. |
Method | not |
implement the ``NOT ILIKE`` operator. |
Method | not |
implement the ``NOT IN`` operator. |
Method | not |
implement the ``NOT LIKE`` operator. |
Method | notilike |
Undocumented |
Method | notin_ |
Undocumented |
Method | notlike |
Undocumented |
Method | nulls |
Produce a :func:`_expression.nulls_first` clause against the parent object. |
Method | nulls |
Produce a :func:`_expression.nulls_last` clause against the parent object. |
Method | nullsfirst |
Undocumented |
Method | nullslast |
Undocumented |
Method | op |
Produce a generic operator function. |
Method | regexp |
Implements a database-specific 'regexp match' operator. |
Method | regexp |
Implements a database-specific 'regexp replace' operator. |
Method | startswith |
Implement the ``startswith`` operator. |
Property | _propagate |
Undocumented |
Inherited from ColumnOperators
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
):
Method | __lshift__ |
implement the << operator. |
Method | __rshift__ |
implement the >> operator. |
Method | bitwise |
Produce a bitwise AND operation, typically via the ``&`` operator. |
Method | bitwise |
Produce a bitwise LSHIFT operation, typically via the ``<<`` operator. |
Method | bitwise |
Produce a bitwise NOT operation, typically via the ``~`` operator. |
Method | bitwise |
Produce a bitwise OR operation, typically via the ``|`` operator. |
Method | bitwise |
Produce a bitwise RSHIFT operation, typically via the ``>>`` operator. |
Method | bitwise |
Produce a bitwise XOR operation, typically via the ``^`` operator, or ``#`` for PostgreSQL. |
Method | icontains |
Implement the ``icontains`` operator, e.g. case insensitive version of :meth:`.ColumnOperators.contains`. |
Method | iendswith |
Implement the ``iendswith`` operator, e.g. case insensitive version of :meth:`.ColumnOperators.endswith`. |
Method | isnot |
Undocumented |
Method | istartswith |
Implement the ``istartswith`` operator, e.g. case insensitive version of :meth:`.ColumnOperators.startswith`. |
Class Variable | timetuple |
Hack, allows datetime objects to be compared on the LHS. |
Method | _rconcat |
Implement an 'rconcat' operator. |
Inherited from DQLDMLClauseElement
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
):
Method | compile |
Compile this SQL expression. |
Method | _compiler |
Return a compiler appropriate for this ClauseElement, given a Dialect. |
Inherited from ClauseElement
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
):
Method | __bool__ |
Undocumented |
Method | __getstate__ |
Undocumented |
Method | __repr__ |
Undocumented |
Method | compare |
Compare this :class:`_expression.ClauseElement` to the given :class:`_expression.ClauseElement`. |
Method | get |
Return immediate child :class:`.visitors.HasTraverseInternals` elements of this :class:`.visitors.HasTraverseInternals`. |
Method | params |
Return a copy with :func:`_expression.bindparam` elements replaced. |
Method | unique |
Return a copy with :func:`_expression.bindparam` elements replaced. |
Class Variable | is |
Undocumented |
Class Variable | is |
Undocumented |
Class Variable | is |
Undocumented |
Class Variable | negation |
Undocumented |
Property | entity |
Undocumented |
Method | _clone |
Create a shallow copy of this ClauseElement. |
Method | _cloned |
Return the set consisting all cloned ancestors of this ClauseElement. |
Method | _compile |
Undocumented |
Method | _execute |
Undocumented |
Method | _execute |
an additional hook for subclasses to provide a different implementation for connection.scalar() vs. connection.execute(). |
Method | _negate |
a hook to allow the right side of a binary expression to respond to a negation of the binary expression. |
Method | _replace |
Undocumented |
Method | _set |
Undocumented |
Method | _ungroup |
Return this :class:`_expression.ClauseElement` without any groupings. |
Method | _with |
in the context of binary expression, convert the type of this object to the one given. |
Class Variable | _cache |
Undocumented |
Class Variable | _gen |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Class Variable | _is |
Undocumented |
Property | _constructor |
return the 'constructor' for this ClauseElement. |
Property | _from |
Undocumented |
Property | _order |
Undocumented |
Inherited from SupportsWrappingAnnotations
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
):
Method | _annotate |
return a copy of this ClauseElement with annotations updated by the given dictionary. |
Method | _deannotate |
return a copy of this :class:`_expression.ClauseElement` with annotations removed. |
Method | _with |
return a copy of this ClauseElement with annotations replaced by the given dictionary. |
Inherited from SupportsAnnotations
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
, SupportsWrappingAnnotations
):
Method | _gen |
Undocumented |
Property | _annotations |
Undocumented |
Inherited from MemoizedHasCacheKey
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
, SupportsWrappingAnnotations
, SupportsAnnotations
):
Method | _generate |
return a cache key. |
Inherited from HasCacheKey
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
, SupportsWrappingAnnotations
, SupportsAnnotations
, MemoizedHasCacheKey
):
Class Variable | inherit |
Indicate if this :class:`.HasCacheKey` instance should make use of the cache key generation scheme used by its immediate superclass. |
Class Method | _generate |
generate cache key dispatcher for a new class. |
Class Method | _generate |
Undocumented |
Method | _gen |
return an optional cache key. |
Class Variable | _generated |
Undocumented |
Class Variable | _hierarchy |
private attribute which may be set to False to prevent the inherit_cache warning from being emitted for a hierarchy of subclasses. |
Class Variable | _is |
Undocumented |
Inherited from HasCopyInternals
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
, SupportsWrappingAnnotations
, SupportsAnnotations
, MemoizedHasCacheKey
, HasCacheKey
):
Method | _copy |
Reassign internal elements to be clones of themselves. |
Inherited from HasTraverseInternals
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
, SupportsWrappingAnnotations
, SupportsAnnotations
, MemoizedHasCacheKey
, HasCacheKey
, HasCopyInternals
, ExternallyTraversible
):
Class Variable | _traverse |
Undocumented |
Inherited from CompilerElement
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
, SupportsWrappingAnnotations
, SupportsAnnotations
, MemoizedHasCacheKey
, HasCacheKey
, HasCopyInternals
, ExternallyTraversible
, HasTraverseInternals
):
Method | __str__ |
Undocumented |
Class Variable | stringify |
Undocumented |
Class Variable | supports |
Undocumented |
Inherited from Visitable
(via KeyedColumnElement
, ColumnElement
, ColumnArgumentOrKeyRole
, ColumnArgumentRole
, StatementOptionRole
, WhereHavingRole
, OnClauseRole
, BinaryElementRole
, OrderByRole
, ColumnsClauseRole
, AllowsLambdaRole
, ByOfRole
, UsesInspection
, ColumnListRole
, LimitOffsetRole
, DMLColumnRole
, DDLConstraintColumnRole
, DDLExpressionRole
, StructuralRole
, SQLColumnExpression
, SQLCoreOperations
, ExpressionElementRole
, TypedColumnsClauseRole
, ColumnOperators
, Operators
, SQLRole
, DQLDMLClauseElement
, ClauseElement
, SupportsWrappingAnnotations
, SupportsAnnotations
, MemoizedHasCacheKey
, HasCacheKey
, HasCopyInternals
, ExternallyTraversible
, HasTraverseInternals
, CompilerElement
):
Method | __class |
Undocumented |
Method | __init |
Undocumented |
Class Method | _generate |
Undocumented |
Method | _compiler |
Undocumented |
Class Variable | _original |
Undocumented |
sqlalchemy.sql.elements.ColumnClause
, sqlalchemy.sql.elements.Label
, sqlalchemy.sql.elements.TableValuedColumn
The 'key' that in some circumstances refers to this object in a Python namespace. This typically refers to the "key" of the column as present in the ``.c`` collection of a selectable, e.g. ``sometable.c["somekey"]`` would return a :class:`_schema.Column` with a ``.key`` of "somekey".
OperatorType
, obj: Any
, type_: Optional[ TypeEngine[ _T]]
= None, expanding: bool
= False) -> BindParameter[ _T]
:
(source)
¶
sqlalchemy.sql.elements.Label
Undocumented
sqlalchemy.sql.elements.ColumnClause
Return True if the given column element compares to this one when targeting within a result row.
FromClause
, *, name: Optional[ str]
= None, key: Optional[ str]
= None, name_is_truncatable: bool
= False, compound_select_cols: Optional[ Sequence[ ColumnElement[ Any]]]
= None, disallow_is_literal: bool
= False, **kw: Any
) -> typing_Tuple[ str, ColumnClause[ _T]]
:
(source)
¶
Create a new :class:`_expression.ColumnElement` representing this :class:`_expression.ColumnElement` as it appears in the select list of a descending selectable.
the 'name' that naturally applies this element when rendered in SQL. Concretely, this is the "name" of a column or a label in a SELECT statement; ``<columnname>`` and ``<labelname>`` below:: SELECT <columnmame> FROM table SELECT column AS <labelname> FROM table Above, the two names noted will be what's present in the DBAPI ``cursor.description`` as the names. If this attribute returns ``None``, it means that the SQL element as written does not have a 100% fully predictable "name" that would appear in the ``cursor.description``. Examples include SQL functions, CAST functions, etc. While such things do return names in ``cursor.description``, they are only predictable on a database-specific basis; e.g. an expression like ``MAX(table.col)`` may appear as the string ``max`` on one database (like PostgreSQL) or may appear as the whole expression ``max(table.col)`` on SQLite. The default implementation looks for a ``.name`` attribute on the object, as has been the precedent established in SQLAlchemy for many years. An exception is made on the ``FunctionElement`` subclass so that the return value is always ``None``. .. versionadded:: 1.4.21
A flag used by select._columns_plus_names that helps to determine we are actually going to render in terms of "SELECT <col> AS <label>". This flag can be returned as False for some Column objects that want to be rendered as simple "SELECT <col>"; typically columns that don't have any parent table and are named the same as what the label would be in any case.
table qualified label based on column key. for table-bound columns this is <tablename>_<column key/proxy key>; all other expressions it resolves to key/proxy key.