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 :)
        )

如果我尝试：

.order_by(desc(model.Entry.amount))

然后我得到：NameError: global name 'desc' is not defined。

How can I use ORDER BY descending in a SQLAlchemy query like the following?

This query works, but returns them in ascending order:

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 :)
        )

If I try:

.order_by(desc(model.Entry.amount))

then I get: NameError: global name 'desc' is not defined.

回答 0

与FYI一样，您也可以将这些内容指定为列属性。例如，我可能已经做过：

.order_by(model.Entry.amount.desc())

这很方便，因为它避免了import，并且可以在其他地方（例如关系定义等）中使用它。

有关更多信息，您可以参考此

Just as an FYI, you can also specify those things as column attributes. For instance, I might have done:

.order_by(model.Entry.amount.desc())

This is handy since it avoids an import, and you can use it on other places such as in a relation definition, etc.

For more information, you can refer this

回答 1

from sqlalchemy import desc
someselect.order_by(desc(table1.mycol))

来自@ jpmc26的用法

from sqlalchemy import desc
someselect.order_by(desc(table1.mycol))

Usage from @jpmc26

回答 2

您可能要做的另一件事是：

.order_by("name desc")

这将导致：ORDER BY名称desc。这里的缺点是按顺序使用显式列名。

One other thing you might do is:

.order_by("name desc")

This will result in: ORDER BY name desc. The disadvantage here is the explicit column name used in order by.

回答 3

您可以`.desc()`像这样在查询中使用函数

query = (model.Session.query(model.Entry)
        .join(model.ClassificationItem)
        .join(model.EnumerationValue)
        .filter_by(id=c.row.id)
        .order_by(model.Entry.amount.desc())
        )

这将按金额降序排列，或者

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)
)
)

对于官方文档，请使用链接或检查以下代码段

sqlalchemy.sql.expression.desc（column）产生一个降序的ORDER BY子句元素。

例如：
from sqlalchemy import desc

stmt = select([users_table]).order_by(desc(users_table.c.name))
将产生如下SQL：
SELECT id, name FROM user ORDER BY name DESC
desc（）函数是ColumnElement.desc（）方法的独立版本，可用于所有SQL表达式，例如：
stmt = select([users_table]).order_by(users_table.c.name.desc())
参数column –一个ColumnElement（例如标量SQL表达式），用于应用desc（）操作。

也可以看看

asc（）

nullsfirst（）

nullslast（）

Select.order_by（）

You can use `.desc()` function in your query just like this

query = (model.Session.query(model.Entry)
        .join(model.ClassificationItem)
        .join(model.EnumerationValue)
        .filter_by(id=c.row.id)
        .order_by(model.Entry.amount.desc())
        )

This will order by amount in descending order or

query = session.query(
    model.Entry
).join(
    model.ClassificationItem
).join(
    model.EnumerationValue
).filter_by(
    id=c.row.id
).order_by(
    model.Entry.amount.desc()
)
)

Use of desc function of SQLAlchemy

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)
)
)

For official docs please use the link or check below snippet

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()

回答 4

你可以试试： .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()

You can try: .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()

回答 5

@Radu答案的补充，与SQL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")

Complementary at @Radu answer, As in SQL, you can add the table name in the parameter if you have many table with the same attribute.

.order_by("TableName.name desc")

Python 实用宝典

SQLAlchemy按降序排列？

问题：SQLAlchemy按降序排列？