All you need to do is to specify the interval you're looking for, and it will convert your string into a valid INTERVAL datatype. Intervals are DAY, HOUR, MINUTE, SECOND
Examples:
Turn 2 days into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '2' DAY) FROM DUAL; TO_DSINTERVAL(INTERVAL'2'DAY) -------------------------------------------------- +02 00:00:00.000000 1 row selected.
Turn 75 minutes into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '75' MINUTE) FROM DUAL; TO_DSINTERVAL(INTERVAL'75'MINUTE) -------------------------------------------------- +00 01:15:00.000000 1 row selected.
Turn 60 minutes into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '60' MINUTE) FROM DUAL; TO_DSINTERVAL(INTERVAL'60'MINUTE) -------------------------------------------------- +00 01:00:00.000000 1 row selected.
Turn 60 seconds into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '60' SECOND) FROM DUAL; TO_DSINTERVAL(INTERVAL'60'SECOND) -------------------------------------------------- +00 00:01:00.000000 1 row selected.
Turn 24 hours into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '24' HOUR) FROM DUAL; TO_DSINTERVAL(INTERVAL'24'HOUR) -------------------------------------------------- +01 00:00:00.000000 1 row selected.
Turn 6 hours into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '6' HOUR) FROM DUAL; TO_DSINTERVAL(INTERVAL'6'HOUR) -------------------------------------------------- +00 06:00:00.000000 1 row selected.Turn 61.2 seconds into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '61.2' SECOND) FROM DUAL; TO_DSINTERVAL(INTERVAL'61.2'SECOND) -------------------------------------------------- +00 00:01:01.200000 1 row selected.Turn 1 hour into a valid INTERVAL datatype
SELECT TO_DSINTERVAL(INTERVAL '1' HOUR) FROM DUAL; TO_DSINTERVAL(INTERVAL'1'HOUR) -------------------------------------------------- +00 01:00:00.000000 1 row selected.