Tagged Questions

6
votes
3answers
87 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) ...
0
votes
1answer
102 views

Select first row (grouping) + add aggregate function

First have a look at this question on StackOverflow. I'm looking to accomplish the same task, except I also need to add an aggregate function (PostGIS's ST_Union) to my query. How can I combine the ...
1
vote
0answers
143 views

How to calculate running total based on dynamic values?

I need to calculate the running total in which the target column is changing along with the time. Its something which aws does. Charging based for only what you use. So how do I aggregate sum of ...
3
votes
1answer
86 views

Aggregating statistics from child rows

I have a parent row and then many child rows, and I must aggregate statistics from these child rows. For a more concrete example let's imagine I have one round of golf (parent row) and then child ...
4
votes
1answer
204 views

Is it possible to wrap aggregate functions in Postgres?

Postgres' string_agg(expr, delimiter) function is great. But I would like to have a version that takes a single argument -- the field to aggregate -- and assumes a delimiter of ', ' since that is ...
2
votes
2answers
501 views

postgresql view with max min with id

I have the following table: CREATE TABLE trans ( id SERIAL PRIMARY KEY, trans_date date, trans_time time ); I want to have the following view CREATE OR REPLACE VIEW daily_trans ...
0
votes
0answers
43 views

postgresql view [duplicate]

Possible Duplicate: postgresql view with max min with id I have the following table: CREATE TABLE trans ( id SERIAL PRIMARY KEY, trans_date date, trans_time time ); I ...
4
votes
5answers
6k views

How can I use a default value in a Select query in PostgreSQL?

I would like to use a default value for a column that should be used if no rows is returned. Is that possible in PostgreSQL? How can I do it? Or is there any other way I can solve this? E.g. ...