FW: SQL rolling window without aggregation

It seems like it's not been sent to the SQL group, so I'm trying with this group.

Thanks,
Suya

From: Huang, Suya
Sent: Friday, December 05, 2014 6:25 PM
To: 'pgsql-sql(at)postgresql(dot)org'
Subject: [SQL] rolling window without aggregation

Hi SQL experts,

I've got a question here, is that possible to implement a window function without aggregation? Any SQL could get below desired result?

For example:

Table input
date | id
------------+--------
2014-04-26 | A
2014-05-03 | B
2014-05-10 | C
2014-05-17 | D
2014-05-24 | E
2014-05-31 | F

Expected output, use 2 week roll up as an example:
date | id
------------+--------
2014-04-26 | A
2014-05-03 | A
2014-05-03 | B
2014-05-10 | B
2014-05-10 | C
2014-05-17 | C
2014-05-17 | D
2014-05-24 | D
2014-05-24 | E
2014-05-31 | E
2014-05-31 | F

Thanks,
Suya