Python sqlalchemy 模块，nullsfirst() 实例源码
我们从Python开源项目中，提取了以下50个代码示例，用于说明如何使用sqlalchemy.nullsfirst()。
def _create_nullsfirst(cls, column):
"""Produce the ``NULLS FirsT`` modifier for an ``ORDER BY`` expression.
:func:`.nullsfirst` is intended to modify the expression produced
by :func:`.asc` or :func:`.desc`,and indicates how NULL values
should be handled when they are encountered during ordering::
from sqlalchemy import desc,nullsfirst
stmt = select([users_table]).\\
order_by(nullsfirst(desc(users_table.c.name)))
The sql expression from the above would resemble::
SELECT id,name FROM user ORDER BY name DESC NULLS FirsT
Like :func:`.asc` and :func:`.desc`,:func:`.nullsfirst` is typically
invoked from the column expression itself using
:meth:`.ColumnElement.nullsfirst`,rather than as its standalone
function version,as in::
stmt = (select([users_table]).
order_by(users_table.c.name.desc().nullsfirst())
)
.. seealso::
:func:`.asc`
:func:`.desc`
:func:`.nullslast`
:meth:`.Select.order_by`
"""
return UnaryExpression(
_literal_as_label_reference(column),
modifier=operators.nullsfirst_op,
wraps_column_expression=False)
def _create_nullslast(cls, column):
"""Produce the ``NULLS LAST`` modifier for an ``ORDER BY`` expression.
:func:`.nullslast` is intended to modify the expression produced
by :func:`.asc` or :func:`.desc`,nullslast
stmt = select([users_table]).\\
order_by(nullslast(desc(users_table.c.name)))
The sql expression from the above would resemble::
SELECT id,name FROM user ORDER BY name DESC NULLS LAST
Like :func:`.asc` and :func:`.desc`,:func:`.nullslast` is typically
invoked from the column expression itself using
:meth:`.ColumnElement.nullslast`,as in::
stmt = select([users_table]).\\
order_by(users_table.c.name.desc().nullslast())
.. seealso::
:func:`.asc`
:func:`.desc`
:func:`.nullsfirst`
:meth:`.Select.order_by`
"""
return UnaryExpression(
_literal_as_label_reference(column),
modifier=operators.nullslast_op,
wraps_column_expression=False)
def _create_desc(cls, column):
"""Produce a descending ``ORDER BY`` clause element.
e.g.::
from sqlalchemy import desc
stmt = select([users_table]).order_by(desc(users_table.c.name))
will produce sql as::
SELECT id,name FROM user ORDER BY name DESC
The :func:`.desc` function is a standalone version of the
:meth:`.ColumnElement.desc` method available on all sql expressions,
e.g.::
stmt = select([users_table]).order_by(users_table.c.name.desc())
:param column: A :class:`.ColumnElement` (e.g. scalar sql expression)
with which to apply the :func:`.desc` operation.
.. seealso::
:func:`.asc`
:func:`.nullsfirst`
:func:`.nullslast`
:meth:`.Select.order_by`
"""
return UnaryExpression(
_literal_as_label_reference(column),
modifier=operators.desc_op,
wraps_column_expression=False)
def _create_asc(cls, column):
"""Produce an ascending ``ORDER BY`` clause element.
e.g.::
from sqlalchemy import asc
stmt = select([users_table]).order_by(asc(users_table.c.name))
will produce sql as::
SELECT id,name FROM user ORDER BY name ASC
The :func:`.asc` function is a standalone version of the
:meth:`.ColumnElement.asc` method available on all sql expressions,
e.g.::
stmt = select([users_table]).order_by(users_table.c.name.asc())
:param column: A :class:`.ColumnElement` (e.g. scalar sql expression)
with which to apply the :func:`.asc` operation.
.. seealso::
:func:`.desc`
:func:`.nullsfirst`
:func:`.nullslast`
:meth:`.Select.order_by`
"""
return UnaryExpression(
_literal_as_label_reference(column),
modifier=operators.asc_op,
wraps_column_expression=False)
def _create_desc(cls,
e.g.::
stmt = select([users_table]).order_by(users_table.c.name.desc())
:param column: A :class:`.ColumnElement` (e.g. scalar sql expression)
with which to apply the :func:`.desc` operation.
.. seealso::
:func:`.asc`
:func:`.nullsfirst`
:func:`.nullslast`
:meth:`.Select.order_by`
"""
return UnaryExpression(
_literal_as_text(column), modifier=operators.desc_op)
def _create_asc(cls,
e.g.::
stmt = select([users_table]).order_by(users_table.c.name.asc())
:param column: A :class:`.ColumnElement` (e.g. scalar sql expression)
with which to apply the :func:`.asc` operation.
.. seealso::
:func:`.desc`
:func:`.nullsfirst`
:func:`.nullslast`
:meth:`.Select.order_by`
"""
return UnaryExpression(
_literal_as_text(column), modifier=operators.asc_op)
def _create_nullslast(cls,nullslast
stmt = select([users_table]).\
order_by(nullslast(desc(users_table.c.name)))
The sql expression from the above would resemble::
SELECT id,as in::
stmt = select([users_table]).\
order_by(users_table.c.name.desc().nullslast())
.. seealso::
:func:`.asc`
:func:`.desc`
:func:`.nullsfirst`
:meth:`.Select.order_by`
"""
return UnaryExpression(
_literal_as_label_reference(column),
wraps_column_expression=False)
def _create_nullsfirst(cls,
wraps_column_expression=False)
def _create_nullslast(cls,
wraps_column_expression=False)
def _create_nullsfirst(cls,
wraps_column_expression=False)
def _create_nullslast(cls,
wraps_column_expression=False)
def _create_nullsfirst(cls,
wraps_column_expression=False)
def _create_nullsfirst(cls,
wraps_column_expression=False)
def _create_nullslast(cls,
wraps_column_expression=False)
def _create_desc(cls,
wraps_column_expression=False)
def _create_asc(cls,
wraps_column_expression=False)
def _create_nullsfirst(cls,
wraps_column_expression=False)
def _create_nullslast(cls,
wraps_column_expression=False)