How to convert in SQL the number of seconds into a human-readable duration?

Question

In a SQL-database I make some selects, that get an duration (as result of a subtraction between two dates) in seconds as an int. But I want to format this result in a human-readable form like 'hh:mm' or 'dd:hh'. Is that possible in SQL and how can I realize this?

Answer 1

In SQL 2005, You can use the following:

    select convert(varchar(8), dateadd(second, [SecondsColumn], 0),  108)

Which first converts the seconds into a date after 1900-01-01, and then gets the hh:mm:ss part.

If the column is more than 24 hours, this will roll over, if you want days and then hours in that case just do something like:

case when SecondsColumn> (24*60*60) 
     then 
      cast(datepart(day,datediff(dd, 0, dateadd(second, SecondsColumn, 0))) as varchar(4))
     + 'd' + convert(varchar(2), dateadd(second, SecondsColumn, 0), 108) 
    else
      convert(varchar(8), dateadd(second, SecondsColumn, 0), 108) 
    end

Answer 2

Every database does it differently. I use PostgreSQL and it does it like so:

select to_char(my_date - my_other_date, 'HH:MM:SS');

You'll have to consult the manual for the database you are using.

Answer 3

Assuming you have seconds:

DECLARE @DurationSeconds INT

-- 25h 45m 14s
SET @DurationSeconds = (25 * 3600) + (45 * 60) + (14)

SELECT 
  @DurationSeconds, 
  @DurationSeconds / 3600 hours, 
  @DurationSeconds % 3600 / 60 minutes,
  @DurationSeconds % (3600 / 60) seconds

I'll let the task of formatting that nicely to you. :-)

Answer 4

There is no standard, though many DBMSs have their own custom syntax.

In general it is better to be doing formatting-for-human-readability work in your application's presentation layer rather than anywhere near the database.