Warwick Prince wrote:
>
> Hi Simon
>
> Thanks for that - I knew it was something wrong with the approach but
> simply could not pick it! Back to the test bench for another go :-)
>
> Cheers
> Warwick
>
> P.S. OK - I have to ask - when and how (why?) do I do the .join on
> the query? ;-)
>
In SQL, you can treat a query just like a table, so you can join 2
queries together, or join a query to another table. For example:
SELECT *
FROM
(SELECT a, b FROM table_1) as q1
INNER JOIN
(SELECT c, d FROM table_2) as q2
ON q1.b = q2.c
That example is not very helpful - it could easily be rewritten as a
single SELECT, but I hope you see that the subqueries can be as
complicated as you like.
The object that you were originally producing with your 'q.join(price)'
wasn't a Select object, but a Join - something that you can select from.
You could write something like this:
# JOIN the price table with a query on the products table:
j = prod.select().join(price)
# SELECT from that JOIN:
q = select(<some_columns>, from_obj=[j])
This almost certainly isn't what you wanted in your situation, but there
are plenty of cases where subqueries are very useful.
Hope that helps,
Simon
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