1
vote
1answer
102 views

Aliases with correlated subqueries

I am looking at an example of correlated subquery with aliases from a PostgreSQL book: bpsimple=# SELECT * FROM orderinfo o, bpsimple=# (SELECT * FROM customer c WHERE town = 'Bingham') c bpsimple=# ...
0
votes
1answer
48 views

Append columns with values from has many reletionship

I have two tables orders and items. Every Order has many Items. orders - id - created_at - paid_at items - id - title - amount - quantity - order_id Let say that there are 3 kinds of items. Chair, ...
6
votes
3answers
279 views

Is using SUM() twice suboptimal?

I know I have to write SUM twice, if I wish to use it in a HAVING clause (or use a derived table otherwise): SELECT id, sum(hours) AS totalhours FROM mytable GROUP BY id HAVING sum(hours) ...