问题
I want a "group by and count" command in sqlalchemy. How can I do this?
回答1:
The documentation on counting says that for group_by queries it is better to use func.count():
from sqlalchemy import func
session.query(Table.column, func.count(Table.column)).group_by(Table.column).all()
回答2:
You can also count on multiple groups and their intersection:
self.session.query(func.count(Table.column1),Table.column1, Table.column2).group_by(Table.column1, Table.column2).all()
The query above will return counts for all possible combinations of values from both columns.
回答3:
If you are using Table.query property:
from sqlalchemy import func
Table.query.with_entities(Table.column, func.count(Table.column)).group_by(Table.column).all()
If you are using session.query() method (as stated in miniwark's answer):
from sqlalchemy import func
session.query(Table.column, func.count(Table.column)).group_by(Table.column).all()
来源：https://stackoverflow.com/questions/1052148/group-by-count-function-in-sqlalchemy