user1742188 user1742188 - 19 days ago 6
SQL Question

Convert rank and partition query to SqlAlchemy

I would like to convert the following query to SqlAlchemy, but the documentation isn't very helpful:

select * from (
select *,
RANK() OVER (PARTITION BY id ORDER BY date desc) AS RNK
from table1
) d
where RNK = 1


Any suggestions?

Answer

use over expression

from sqlalchemy import func

subquery = db.session.query(
    table1,
    func.rank().over(
        order_by=table1.c.date.desc(),
        partition_by=table1.c.id
    ).label('rnk')
).subquery()

query = db.session.query(subquery).filter(
    subquery.c.rnk==1
)
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