python - sqlalchemy 选择 to_date

Question

连接到 Oracle 数据库，我需要运行以下查询：

SELECT
    ad_campaign_id as campaign_id,
    TO_DATE("DAY", 'YYYY-MM-DD') as DAY,
    NVL(spent, 0) as spent,
    impressions,
    clicks 
FROM sometable

我怎样才能用 SQLAlchemy 做到这一点？如何将参数发送到func.to_date函数？

Answer 1

SQLAlchemy 的func将接受任何 Oracle 函数作为属性。

from sqlalchemy import func

campaign_id = sometable.c.ad_campaign_id
day = func.to_date(sometable.c.day, 'YYYY-MM-DD') # Is this what you need?
spent = func.nvl(sometable.c.spent, 0)
clicks = sometable.c.clicks
cols = [campaign_id, day, spent, clicks]

# Feel free to skip, this is just so you get the labels you want
labels = "campaign_id day spent clicks".split()
col_label = zip(cols, labels)
labelled = [c.label(l) for (c,l) in col_label]

q = session.query(*labelled) # or use *cols if you don't care about labels
q.all()

Answer 2

以下是执行任意查询的方式：

engine.execute(query_string)

设置引擎是另一回事。虽然它有很好的记录。

如果您再次询问如何使用一些不同的模型来做到这一点......

所以这是你问题的第一部分回答（可能）。但是 func.to_date 函数是什么意思？请澄清