如何在SQLAlchemy查询中使用ORDER降序，如下所示?
这个查询是有效的，但是以升序返回它们:
query = (model.Session.query(model.Entry)
.join(model.ClassificationItem)
.join(model.EnumerationValue)
.filter_by(id=c.row.id)
.order_by(model.Entry.amount) # This row :)
)
如果我试着:
.order_by(desc(model.Entry.amount))
那么我得到:NameError:全局名称'desc'没有定义。
当前回答
您可以像这样在查询中使用.desc()函数
query = (model.Session.query(model.Entry)
.join(model.ClassificationItem)
.join(model.EnumerationValue)
.filter_by(id=c.row.id)
.order_by(model.Entry.amount.desc())
)
这将按数量降序排序 或
query = session.query(
model.Entry
).join(
model.ClassificationItem
).join(
model.EnumerationValue
).filter_by(
id=c.row.id
).order_by(
model.Entry.amount.desc()
)
)
使用SQLAlchemy的desc函数
from sqlalchemy import desc
query = session.query(
model.Entry
).join(
model.ClassificationItem
).join(
model.EnumerationValue
).filter_by(
id=c.row.id
).order_by(
desc(model.Entry.amount)
)
)
对于正式文档，请使用链接或检查下面的代码片段
sqlalchemy.sql.expression.desc(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 desc() function is a standalone version of the ColumnElement.desc() method available on all SQL expressions, e.g.: stmt = select([users_table]).order_by(users_table.c.name.desc()) Parameters column – A ColumnElement (e.g. scalar SQL expression) with which to apply the desc() operation. See also asc() nullsfirst() nullslast() Select.order_by()
其他回答
你可以做的另一件事是:
.order_by("name desc")
这将导致:ORDER BY name desc。这里的缺点是在ORDER BY中使用了显式列名。
与SQL中一样，如果您有许多具有相同属性的表，则可以在参数中添加表名。
.order_by("TableName.name desc")
from sqlalchemy import desc
someselect.order_by(desc(table1.mycol))
@jpmc26的用法
您可以像这样在查询中使用.desc()函数
query = (model.Session.query(model.Entry)
.join(model.ClassificationItem)
.join(model.EnumerationValue)
.filter_by(id=c.row.id)
.order_by(model.Entry.amount.desc())
)
这将按数量降序排序 或
query = session.query(
model.Entry
).join(
model.ClassificationItem
).join(
model.EnumerationValue
).filter_by(
id=c.row.id
).order_by(
model.Entry.amount.desc()
)
)
使用SQLAlchemy的desc函数
from sqlalchemy import desc
query = session.query(
model.Entry
).join(
model.ClassificationItem
).join(
model.EnumerationValue
).filter_by(
id=c.row.id
).order_by(
desc(model.Entry.amount)
)
)
对于正式文档，请使用链接或检查下面的代码片段
sqlalchemy.sql.expression.desc(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 desc() function is a standalone version of the ColumnElement.desc() method available on all SQL expressions, e.g.: stmt = select([users_table]).order_by(users_table.c.name.desc()) Parameters column – A ColumnElement (e.g. scalar SQL expression) with which to apply the desc() operation. See also asc() nullsfirst() nullslast() Select.order_by()
您可以尝试:.order_by(ClientTotal.id.desc())
session = Session()
auth_client_name = 'client3'
result_by_auth_client = session.query(ClientTotal).filter(ClientTotal.client ==
auth_client_name).order_by(ClientTotal.id.desc()).all()
for rbac in result_by_auth_client:
print(rbac.id)
session.close()
