TO_CHAR Issue or Designed feature

[Thomas Morgan]

When I issue following

SELECT to_char(now(), 'Hh24') Current_Hour;

I get:

current_hour
--------------
Hh24
(1 row)

Is this documented or it it a flaw. Should it be doing the format case insensitive?

Thanks,
Thomas

[John-Paul Stewart]

Although it is not explicitly stated, the format string must be case
sensitive. You can infer that from the following table:

https://www.postgresql.org/docs/15/functions-formatting.html#FUNCTIONS-FORMATTING-DATETIME-TABLE

Note the difference between "AM" and "am", or "MONTH" and "Month" and
"month". (To name just two examples.) Based on that, it should be
obvious that the pattern has to be interpreted in a case sensitive manner.