TO_DATE with YYYY format mask behavior

Question

I was selecting records from a table where a date in the table is prior to a given year:
SELECT * FROM the_table WHERE date_col <TO_DATE('2006','YYYY');
On January 31st, this worked fine.
On February 1st, I started seeing records from January 2006.
When I run the following in SQL*Plus, the result is 2/1/2006:
SELECT TO_DATE('2006','YYYY') FROM DUAL;
I have used this format before (but perhaps not in the exact situation) and I've never seen this issue before.
SQL*Plus is version 8.0.6.0.0. The result occurs on database versions 10.2.0.3.0 and 10.2.0.4.0.
I'm not understanding why the current date would have any effect on the SELECTed date.
Any insights would be appreciated.
Thanks!

Answer 1

Hi,
When you don't spedcify the month in TO_DATE, it defaults to the current month.
SELECT  SYSDATE
,       TO_DATE ('2006', 'YYYY')
FROM    dual;just produced
02-Feb-2009 01-Feb-2006You have to give the month:
TO_DATE ('200601', 'YYYYMM')Edited by: Frank Kulash on Feb 2, 2009 3:21 PM
Or use TRUNC (..., 'YYYY'), as Walter showed you.