2016-08-07 22:23 GMT+03:00 Tim Smith <randomdev4+postgres@xxxxxxxxx>:
create table test (
when date,
foo numeric,
bar numeric,
alice numeric,
bob numeric);
insert into test values ('2016-01-01',1,2,3,4);
insert into test values ('2016-01-02',5,6,7,8);
insert into test values ('2016-01-03',9,10,11,12);
insert into test values ('2016-01-04',13,14,15,16);
insert into test values ('2016-01-05',17,18,19,20);
I had to rename column "when" into "when_d", as I do not like quoting identifiers.
Try this query with window functions:
SELECT *,lead(foo,4) OVER (ORDER BY when_d),
last_value(foo) OVER (ORDER BY when_d RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
FROM test;
This will give you the ability to lookup needed values.
You'll have to use subquery though, as window functions are evaluated after the `WHERE` clause.
--
Victor Y. Yegorov
