incorrect date time format in Oracle DB, convert to hours and minutes - sql

Question

Don't ask me why but for some reason we have a date time column that is in the wrong format that I need help converting.
Example timestamp from DB: 01-OCT-20 12.18.44.000000000 AM
In the example above the hours is actually 18 and the minutes is 44.
Not sure how this happened by 12 is the default for everything. All I want to do is get the difference in HH:MM from 2 timestamps, but i dont know how to convert this properly with the hours being in the minute section and the minutes being in the seconds section.
Example of what I'm looking for:
01-OCT-20 12.18.44.000000000 AM - 01-OCT-20 12.12.42.000000000 AM
Output: 06:02 . so the timespan would be 6 hours and 2 minutes in this case.
Thanks,

Answer 1

In the example above the hours is actually 18 and the minutes is 44.
Not sure how this happened by 12 is the default for everything. All I want to do is get the difference in HH:MM from 2 timestamps, but i dont know how to convert this properly with the hours being in the minute section and the minutes being in the seconds section.
To convert minutes to hours, you need to multiply by 60.
To convert seconds to minutes, you also need to multiply by 60.
So, if you want to convert the time part of the correct value then you take the time since midnight and multiply it all by 60.
If you want to get the difference between the current and correct time (after multiplying by 60) then you want to subtract the current time (which can be simplified to just multiplying by 59).
So to get the time difference you can use:
SELECT (value - TRUNC(value))*59 AS difference,
value + (value - TRUNC(value))*59 AS updated_value
FROM table_name;
So, for your sample data:
CREATE TABLE table_name ( value ) AS
SELECT TO_TIMESTAMP( '01-OCT-20 12.18.44.000000000 AM', 'DD-MON-RR HH12.MI.SS.FF9 AM' ) FROM DUAL
Then the output is:
DIFFERENCE | UPDATED_VALUE
:---------------------------- | :-------------------------
+000000000 18:25:16.000000000 | 2020-10-01 18:44:00.000000
db<>fiddle here
If you want to compare two wrong values just subtract one timestamp from the other and multiply by 60 (assuming that the hour will always be 12 AM or 00 in the 24 hour clock):
SELECT (value1 - value2) * 60 AS difference,
value1,
value1 + (value1 - TRUNC(value1))*59 AS updated_value1,
value2,
value2 + (value2 - TRUNC(value2))*59 AS updated_value2
FROM table_name;
So, for the sample data:
CREATE TABLE table_name ( value1, value2 ) AS
SELECT TO_TIMESTAMP( '01-OCT-20 12.18.44.000000000 AM', 'DD-MON-RR HH12.MI.SS.FF9 AM' ),
TO_TIMESTAMP( '01-OCT-20 12.12.42.000000000 AM', 'DD-MON-RR HH12.MI.SS.FF9 AM' )
FROM DUAL
The output is:
DIFFERENCE | VALUE1 | UPDATED_VALUE1 | VALUE2 | UPDATED_VALUE2
:---------------------------- | :------------------------- | :------------------------- | :------------------------- | :-------------------------
+000000000 06:02:00.000000000 | 2020-10-01 00:18:44.000000 | 2020-10-01 18:44:00.000000 | 2020-10-01 00:12:42.000000 | 2020-10-01 12:42:00.000000
Which gives the difference as 6 hours and 2 minutes.
db<>fiddle here