`sum`、`average`、`min`、`max`的sqlalchemy简单示例 [英] sqlalchemy simple example of `sum`, `average`, `min`, `max`

问题描述

对于sqlalchemy，谁能轻轻举出sum、average、等SQL函数的简单例子>min、max，为一列(以下以score为例).

For sqlalchemy, Who can gently give simple examples of SQL functions like sum, average, min, max, for a column (score in the following as an example).

至于这个映射器:

class Score(Base):
    #...
    name = Column(String)
    score= Column(Integer)
    #...

推荐答案

参见 SQL表达式语言教程的用法.下面的代码显示了用法:

See SQL Expression Language Tutorial for the usage. The code below shows the usage:

from sqlalchemy.sql import func
qry = session.query(func.max(Score.score).label("max_score"), 
                    func.sum(Score.score).label("total_score"),
                    )
qry = qry.group_by(Score.name)
for _res in qry.all():
    print _res

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