When you subtracted the 2 dates and multipled by 1440, you created an integer. The date format is gone and you cannot directly get HH:MI:SS using to_char.
Are you trying to figure out how many hours, minutes and seconds are between the 2 dates? If so...let's use 44645 as the number of seconds calculated..
For hours, divide the result by 3600 and trunacte the result for hours: floor(44645/3600) = 12 hours
For minutes, take the even remainder (mod) of the number of hours: floor(mod(44645,3600)/60) = 24 minutes
For seconds, take the even remainder (mod) of the number of minutes: mod(mod(44645,3600),60) = 5 seconds
I hope this is what you needed.
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Thomas V. Flaherty Jr.
Birch Hill Technology Group, Inc.