Oracle数据库的TO_TIMESTAMP函数

Question

TO_TIMESTAMP('2018-09-07 18:43:56.302000', 'YYYY-MM-DD hh24:mi:ss.ff')

TO_TIMESTAMP('2018-09-07 18:43:56.302000', 'YYYY-MM-DD HH24:MI:SS.FF')

Hi, is there any difference if I use hh24 instead of HH24 in TO_TIMESTAMP ? same thing also for mi instead of MI , or ssv instead of SS`?

Answer 1

When you convert FROM string TO timestamp, the case is irrelevant. Oracle will even accept Mon for month, when the input is written as AUG or aug .

The case used in the format model only matters when you convert FROM timestamp TO string, and even then, only for the components whose output is in letters, not digits. So, even for TO_CHAR , it doesn't matter if you write YYYY or yyyy or YyyY for the year, they will all be accepted and give the same result. The only difference is that MON will return AUG , Mon will return Aug and mon will return aug . And similar for elements like Dy and DAY , etc.

So, the answer to your question is "it doesn't matter" for TWO independent reasons: capitalization doesn't matter when you convert FROM string TO timestamp, and it doesn't matter for numeric (as opposed to "text") elements anyway. All versions are valid and produce the same result.