如何在flask-sqlalchemy的单行中同时包含SELECT语句中的SUM和COUNT

Question

I'm very new to the programming world. Recently, I've been trying to rewrite sqlite codes in python 3.6 to flask-sqlalchemy and I'd like to know how to rewrite the following code in flask-sqlalchemy in a single statement and pass the selected values into a single variable just as in the code:

rows = db.execute("SELECT SUM(student_total) AS stdtotal, SUM(payment_total) AS paytotal, COUNT(identifier) AS clstotal FROM classes WHERE admin_id = :admID", admID=session["user_id"])

I have read this: http://wiki.workassis.com/sum-avg-count-max-group_by-distinct-sqlalchemy/ but I need to import func from sqlalchemy and if possible, I wish to avoid doing so.

Thank you very much in advance.

Answer 1

I have solved it, thanks to Ilja Everilä's comment and some further readings. I tried using the func library and it works. I guess it's not possible for me to avoid using func. For the new flask-sqlalchemy users who may encounter the same problem as I did in the future, I will write out the solution that I have come up with:

Note: This solution needs to import label from sqlalchemy.sql

rows = db.session.query(label('stdtotal', db.func.sum(classes.student_total)), label('paytotal', db.func.sum(classes.payment_total)), label('clstotal', db.func.count(classes.identifier))).filter_by(admin_id=session["user_id"])

**Please note that the type of the return value of the above query is not the same as that of the sqlite SELECT statement. For sqlite, the return value is a dictionary but for the flask-sqlalchemy, the return value is an object. (See http://docs.sqlalchemy.org/en/latest/orm/query.html )