Oracle to_date () and 24-hour notation and display of MM minutes

Oracle's solution is to_date () and 24-hour notation and the display of MM minutes:
I. Many JavaProgramLike me, the engineer may intuitively convert the format "yyyy-mm-dd hh: mm: SS", but it may cause an error in Oracle: "ora 01810 formatCodeAppears twice ".

For example:

SQL code

Select to_date ('1970-01-01 13:14:20 ', 'yyyy-mm-dd hh24: mm: ss') from dual;

The reason is that SQL statements are case-insensitive. mm and mm are considered to be the same format code, so Oracle SQL uses Mi instead of minutes.

SQL code

Select to_date ('1970-01-01 13:14:20 ', 'yyyy-mm-dd hh24: MI: ss') from dual;

2. Another 24-hour format is used to display hh24.

SQL code

Select to_char (sysdate, 'yyyy-mm-dd hh24: MI: ss') from dual; // Mi is a minute select to_char (sysdate, 'yyyy-mm-dd hh24: MM: ss') from dual; // mm displays the month