折腾：
【已解决】Flask中SQLAlchemy去实现查询后的分页结果的排序
期间，
已经知道了：
SQLAlchemy中order_by去对query结果排序，想要降序，倒序的话，用desc()
而很多例子中：
print query2.order_by(User.name).all() print query2.order_by(User.name.desc()).all() |
感觉是：
order_by默认没有传递参数，不知道是不是就是，升序 的意思
以及，升序的话，写法是不是写成asc()
想要知道：
和desc（降序，descending）对应的，默认的，是不是叫做asc==升序的ascending
SQLAlchemy ORDER BY DESCENDING in Query object?-敲代码
Query API — SQLAlchemy 1.1 Documentation
order_by(*criterion) apply one or more ORDER BY criterion to the query and return the newly resulting Query All existing ORDER BY settings can be suppressed by passing None – this will suppress any ORDER BY configured on mappers as well. Alternatively, passing False will reset ORDER BY and additionally re-allow default mapper.order_by to take place. Note mapper.order_by is deprecated |
SQLAlchey order_by asc
Python sqlalchemy.asc Examples
restaurants = session.query(Restaurant).order_by(asc(Restaurant.name)) |
asc是函数，里面传入的是：类名和属性
postgresql – Multiple order_by sqlalchemy / Flask – Stack Overflow
User.query.order_by(User.popularity.desc(),User.date_created.desc()).limit(10).all() |
SQLAlchemy ORDER BY DESCENDING? – Stack Overflow
.order_by(model.Entry.amount.desc()) 另外也可以： from sqlalchemy import desc someselect.order_by(desc(table1.mycol)) |
SQLALchemy DESC ASC
终于找到官网的解释了：
Column Elements and Expressions — SQLAlchemy 1.1 Documentation
sqlalchemy.sql.expression.asc(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 asc() function is a standalone version of the ColumnElement.asc() method available on all SQL expressions, e.g.: stmt = select([users_table]).order_by(users_table.c.name.asc())
See also 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())
See also |
的确是用：
asc表示升序
-》对应的SQL的也是：
ASC升序和DESC降序
而对于order_by，默认不传递asc的话，
不知道是不是asc
参考：
Selectables, Tables, FROM objects — SQLAlchemy 1.1 Documentation
order_by(*clauses) return a new selectable with the given list of ORDER BY criterion applied. The criterion will be appended to any pre-existing ORDER BY criterion. |
找了半天，也没有找到：
pre-existing的ORDER BY的criterion
在哪里。
【总结】
所以，此处暂时不去操心默认的order_by的配置了。
已经弄清楚了：
order_by可以通过传递asc()或desc()去指定使用升序或降序去排序结果。