SQLAlchemy 按降序排序？

发布于 2025-01-10 03:20:48 字数 502 浏览 0 评论 0原文

如何在 SQLAlchemy 查询中使用 ORDER BY descending ，如下所示？

此查询有效，但按升序返回它们：

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 :)
        )

如果我尝试：

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

然后我得到：NameError：全局名称'desc'未定义。

原文

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.

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海夕 2025-01-17 03:20:48

仅供参考，您还可以将这些内容指定为列属性。例如，我可能会这样做：

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

这很方便，因为它避免了导入，并且您可以在其他地方使用它，例如在关系定义中等。

有关更多信息，您可以参考此< a href="https://docs.sqlalchemy.org/en/14/core/sqlelement.html#sqlalchemy.sql.expression.desc" rel="noreferrer">SQLAlchemy 1.4 文档

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 SQLAlchemy 1.4 Documentation

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苍风燃霜 2025-01-17 03:20:48

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

用法来自@jpmc26

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

Usage from @jpmc26

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岁月打碎记忆 2025-01-17 03:20:48

您可以做的另一件事是：

from sqlalchemy.sql import text
...
.order_by(text("name desc")

这将导致：ORDER BY name desc。这里的缺点是 order by 使用的显式列名。

One other thing you might do is:

from sqlalchemy.sql import text
...
.order_by(text("name desc")

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

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桜花祭 2025-01-17 03:20:48

您可以在查询中使用 .desc() 函数，如下所示：

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

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片段：

sqlalchemy.sql.expression.desc(column) 产生降序 ORDER BY
子句元素。
例如：
from sqlalchemy import desc

stmt = select([users_table]).order_by(desc(users_table.c.name))
将生成 SQL 为：
从用户中选择 ID、姓名 ORDER BY 姓名 DESC
desc() 函数是
ColumnElement.desc() 方法可用于所有 SQL 表达式，例如：
stmt = select([users_table]).order_by(users_table.c.name.desc())
参数列 – ColumnElement（例如标量 SQL 表达式）
应用 desc() 操作。
另请参阅
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()

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如日中天 2025-01-17 03:20:48

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()

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()

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