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sql to sqlalchemy 转换的小例子

　　本文标签：sql,sqlalchemy

复制代码 代码如下:

select to_char(date_published, yyyymm) yo from blog group by yo;

转换成sqlalchemy 语句


可以使用 extract()

复制代码 代码如下:

In[3]: year_field = db.func.extract(year, ArticleModel.date_published)

In[4]: month_field = db.func.extract(month, ArticleModel.date_published)

In[5]: yonth_field = year_field *100+ month_field

In[6]:print db.session.query(yonth_field.label(yonth), db.func.count(1)).group_by(yonth)

SELECT EXTRACT(year FROM article_meta.date_published)*:param_1 + EXTRACT(month FROM article_meta.date_published)AS yonth, count(:param_2)AS count_1 
FROM article_meta JOIN article ON article_meta.id = article.id GROUPBY yonth

也可以 可以通过 func 直接调用数据库支持的函数或存储过程
复制代码 代码如下:

yonth = db.func.to_char(ArticleModel.date_published,yyyymm).label(yonth)
archive_list =(db.session.query(yonth,                                 
    db.func.count(1)).group_by(yonth).all())