Hi,
I have a table with many columns (columnA, columnB, columnC) and I want to
know, how many different entries in columnB are.
I would do such an SQL query:
select distinct columnB from myTable;
I see there is also ``distinct()`` in SQL Alchemy.
However - I am using Class defined ORM like this:
class MyTable(db.Model):
__tablename__ = "myTable"
columnA = db.Column(...)
columnB = db.Column(...)
columnC = db.Column(...)
Thus, I am querying like this:
MyTable.query.all()
The problem seems to be that I was not able to figure out a way to reduce
the columns, e.g. when I add a ``distinct``
MyTable.query.distinct.all()
The distinct function will always use **all** columns.
I also tried ``load_only`` with no success.
I understand, I could define a class, containing only the required column,
then I am told, I should just some ``extend_existing``.
What is the required way to use ``distinct`` in a class based query?
Thanks a lot
Cornelius
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