From 4857e6fe16c2082d23025c03875e6fd74e714ff2 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 30 Sep 2020 15:40:23 -0400 Subject: Fix handling of BC years in to_date/to_timestamp. Previously, a conversion such as to_date('-44-02-01','YYYY-MM-DD') would result in '0045-02-01 BC', as the code attempted to interpret the negative year as BC, but failed to apply the correction needed for our internal handling of BC years. Fix the off-by-one problem. Also, arrange for the combination of a negative year and an explicit "BC" marker to cancel out and produce AD. This is how the negative-century case works, so it seems sane to do likewise. Continue to read "year 0000" as 1 BC. Oracle would throw an error, but we've accepted that case for a long time so I'm hesitant to change it in a back-patch. Per bug #16419 from Saeed Hubaishan. Back-patch to all supported branches. Dar Alathar-Yemen and Tom Lane Discussion: https://postgr.es/m/16419-d8d9db0a7553f01b@postgresql.org --- doc/src/sgml/func.sgml | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'doc/src') diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 258c5bed21f..043c2f841e1 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -5933,8 +5933,18 @@ SELECT regexp_matches('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}'); - The YYYY conversion from string to timestamp or - date has a restriction when processing years with more than 4 digits. You must + In to_timestamp and to_date, + negative years are treated as signifying BC. If you write both a + negative year and an explicit BC field, you get AD + again. An input of year zero is treated as 1 BC. + + + + + + In to_timestamp and to_date, + the YYYY conversion has a restriction when + processing years with more than 4 digits. You must use some non-digit character or template after YYYY, otherwise the year is always interpreted as 4 digits. For example (with the year 20000): -- cgit v1.2.3