Question

Let’s say that I have a range of SQL tables that are named name_YYYY_WW where YYYY = year and WW = week number. If I call upon a function that guides a user defined date to the right table.

If the date entered is "20110101":

SELECT EXTRACT (WEEK FROM DATE '20110101') returns 52 and

SELECT EXTRACT (YEAR FROM DATE '20110101') returns 2011.

While is nothing wrong with these results I want "20110101" to either point to table name_2010_52 or name_2011_01, not name_2011_52 as it does now when I concanate the results to form the query for the table.

Any elegant solutions to this problem?

Answer 1

The function to_char() will allow you to format a date or timestamp to output correct the iso week and iso year.

SELECT to_char('2011-01-01'::date, 'IYYY_IW') as iso_year_week;

will produce:

 iso_year_week 
---------------
 2010_52
(1 row)