aggregate-functions

The Development version of Django has aggregate functions like Avg, Count, Max, Min, StdDev, Sum, and Variance ( link text ). Is there a reason Median is missing from the list? Implementing one seems like it would be easy. Am I missing something? How much are the aggregate functions doing behind the scenes? Because median isn't a SQL aggregate. See, for example, the list of PostgreSQL aggregate functions and the list of MySQL aggregate functions . Mark Chackerian Here's your missing function. Pass it a queryset and the name of the column that you want to find the median for: def median_value

I have an Sql Server Query that is using the ROLLUP clause while grouping. I want an equivalent query in Postgres. Query in SQl Server is: SELECT (CASE WHEN acnt_dba_name Is Null THEN 'Total' ELSE acnt_dba_name END) as account, (CASE WHEN evt_name Is Null THEN '' ELSE evt_name END) as event, COUNT(CASE reg_is_complete WHEN true THEN 1 ELSE Null END) as regsComplete, COUNT(CASE WHEN reg_frn_pro_id > 0 AND reg_is_complete = false THEN 1 ELSE Null END) as regsInComplete, COUNT(CASE WHEN reg_frn_pro_id > 0 THEN Null ELSE 1 END) as regsClicks FROM registrations_view LEFT JOIN events ON (evt_id =

There is no rhyme or reason for this question other than I was curious about how one would go about doing this. Platform: while I was hoping for a SQL-Standard solution, my main concentration is with PostgreSQL 8.4+ . (I know 9.0+ has some array sorting functions.) SELECT id, group, dt FROM foo ORDER BY id; id | group | dt -------+-------+----------- 1 | foo | 2012-01-01 1 | bar | 2012-01-03 1 | baz | 2012-01-02 2 | foo | 2012-01-01 3 | bar | 2012-01-01 4 | bar | 2012-01-01 4 | baz | 2012-01-01 I know the following query is wrong, but the result is similar to what I'm after; a way to tie the

I hope you can help me with this. I have a DF as follows: val df = sc.parallelize(Seq( (1, "a", "2014-12-01", "2015-01-01", 100), (2, "a", "2014-12-01", "2015-01-02", 150), (3, "a", "2014-12-01", "2015-01-03", 120), (4, "b", "2015-12-15", "2015-01-01", 100) )).toDF("id", "prodId", "dateIns", "dateTrans", "value") .withColumn("dateIns", to_date($"dateIns") .withColumn("dateTrans", to_date($"dateTrans")) I would love to do a groupBy prodId and aggregate 'value' summing it for ranges of dates defined by the difference between the column 'dateIns' and 'dateTrans'. In particular, I would like to

I have a table that has the following columns table: route columns: id, location, order_id and it has values such as id, location, order_id 1, London, 12 2, Amsterdam, 102 3, Berlin, 90 5, Paris, 19 Is it possible to do a sql select statement in postgres that will return each row along with the id with the next highest order_id? So I want something like... id, location, order_id, next_id 1, London, 12, 5 2, Amsterdam, 102, NULL 3, Berlin, 90, 2 5, Paris, 19, 3 Thanks select id, location, order_id, lag(id) over (order by order_id desc) as next_id from your_table Creating testbed first: CREATE

In this book I'm currently reading while following a course on databases, the following example of an illegal query using an aggregate operator is given: Find the name and age of the oldest sailor. Consider the following attempt to answer this query: SELECT S.sname, MAX(S.age) FROM Sailors S The intent is for this query to return not only the maximum age but also the name of the sailors having that age. However, this query is illegal in SQL--if the SELECT clause uses an aggregate operation, then it must use only aggregate operations unless the query contains a GROUP BY clause! Some time later

I would like the aggregates of an empty result set to be 0. I have tried the following: SELECT SUM(COALESCE(capacity, 0)) FROM objects WHERE null IS NOT NULL; Result: sum ----- (1 row) Subquestion: wouldn't the above work in Oracle, using SUM(NVL(capacity, 0)) ? From the documentation page about aggregate functions: It should be noted that except for count , these functions return a null value when no rows are selected . In particular, sum of no rows returns null, not zero as one might expect. The coalesce function may be used to substitute zero for null when necessary. So, if you want to