postgresql中的to_date函数如何工作？

Question

select to_date('20170202','YYYYMMDD'); 

回报：

2017-02-02 

但是当我做：

select to_date('20172202','YYYYMMDD'); 

输出为：

2018-10-04 

月份时是错的，为什么不返回一个错误如在甲骨文？

Answer 1

我觉得这里是一个原因，这不会导致一个错误：

to_timestamp and to_date exist to handle input formats that cannot be converted by simple casting. These functions interpret input liberally, with minimal error checking. While they produce valid output, the conversion can yield unexpected results. For example, input to these functions is not restricted by normal ranges, thus to_date('20096040','YYYYMMDD') returns 2014-01-17 rather than causing an error. Casting does not have this behavior.

https://www.postgresql.org/docs/9.6/static/functions-formatting.html

Answer 2

我有什么，我想/ 我使用的TO_CHAR，而不是TO_DATE答案我把fisrt参数转换成日期..

select to_char(DATE '20162202,'YYYYMMDD') into datResult ; 

所以我现在可以有一个错误..

感谢您的帮助大家