SQL Parse Duration String to Seconds - sql-server

Question

I am using SQL Server 12.0.4213.0 and am new to advanced SQL queries.
I have a nvarchar column named duration containing timespans in one of two formats: 39 Seconds if the duration is under 1 minute, else the format is like 1 Day 18 Hours 2 Minutes. Note that each Day/Hour/Minute/Second can be singular or plural. Also in the first format, if the day is 0, the Day will be omitted (same with Hour).
I need to convert the duration to an integer representing total seconds. 1 Minute 30 Seconds should return 90 and 39 Seconds should return 39.
I think this could be completed with a nested CASE statement. The dataset is very large so I want to be sure I am approaching this efficiently. Any help would be appreciated.
One method I have working in PowerShell is to split the duration column on the space character, loop through the resultant array incrementing counter by 2, take array[counter] and multiply it by the corresponding seconds value determined by array[counter+1], add the product to the total seconds sum.

Answer 1

This is a little complicated, but not terrible. The way you can solve this is by removing the Day(s), Hours(s), Minute(s), Second(s) labels from the string, and replacing these with some delimiting string/character.
Then you can split the resulting values using a CTE.
Then, you'll create the timespan in seconds from each part based on it's location in the delimited string.
Finally, sum over the resulting time-span-part-seconds.
EDIT: Now defined as a function
Like so:
CREATE FUNCTION fn_getDurationSeconds(#duration varchar(100)) returns int
as
BEGIN
DECLARE #durationSeconds INT = 0;
with split (duration, part, remainder) as
(
SELECT
duration,
left(duration, CHARINDEX(':', duration)-1),
right(duration, LEN(duration) - CHARINDEX(':', duration))
FROM
(
SELECT
REPLACE(
REPLACE(
REPLACE(
REPLACE(
REPLACE(
REPLACE(
CASE WHEN #duration LIKE '% Day' or #duration like '% Days' THEN #Duration + ' 0 Hours 0 Minutes 0 Seconds'
WHEN #duration LIKE '% Hour' or #duration like '% Hours' THEN #Duration + ' 0 Minutes 0 Seconds'
WHEN #duration LIKE '% Minute'or #duration like '% Minutes' THEN #Duration + ' 0 Seconds'
ELSE #Duration
END, ' Day', ':'),
' Hour', ':'),
' Minute', ':'),
' Second', ':00'),
's', ''),
' ', '') duration
) t
union all
select
duration,
left(remainder, CHARINDEX(':', remainder) - 1),
right(remainder, LEN(remainder) - CHARINDEX(':', remainder))
from split
where CHARINDEX(':', remainder) > 0
)
SELECT #durationSeconds = sum(seconds)
FROM
(
select
duration,
CASE row_number() over(partition by duration order by LEN(remainder) )
WHEN 4 THEN 24 * 60 * 60
WHEN 3 THEN 60 * 60
WHEN 2 THEN 60
WHEN 1 THEN 1
END * CAST(part AS INT) Seconds
from split
) t
group by duration
order by duration
RETURN #durationSeconds
END

Answer 2

Another option is to use substring and patindex and a couple of common table expressions to get the desired result:
First, create and populate a sample table: (Please save us this step in your future questions)
DECLARE #T AS TABLE
(
Duration varchar(40),
NumberOfSeconds int
)
INSERT INTO #T (Duration) VALUES
('39 Seconds'),
('2 Minutes 4 Seconds'),
('1 Hours 7 Minutes 17 Seconds'),
('3 Days 9 Hour 8 Minutes 25 Seconds')
Then, use one cte to hold the patindex results for each word.
This cte is only there to save us the need to write the patindex over and over again.
Add another cte to this one, that will use substring to extract the values for each time part, using the first cte:
;WITH cte1 as
(
SELECT *,
PATINDEX('%Day%', Duration) As DaysIndex,
PATINDEX('%Hour%', Duration) As HoursIndex,
PATINDEX('%Minute%', Duration) As MinutesIndex,
PATINDEX('%Second%', Duration) As SecondIndex
FROM #T
), cte2 as
(
SELECT *,
CASE WHEN DaysIndex > 0 THEN
CAST(SUBSTRING(Duration, 0, DaysIndex) As int) * 60 * 60 * 24
ELSE
0
END As D,
CASE WHEN HoursIndex > 0 THEN
CAST(
SUBSTRING(Duration,
CASE WHEN DaysIndex > 0 THEN DaysIndex + 4
ELSE 0
END,
CASE WHEN DaysIndex > 0 THEN HoursIndex - DaysIndex - 4
ELSE HoursIndex
END
) As int) * 60 * 60
ELSE
0
END As H,
CASE WHEN MinutesIndex > 0 THEN
CAST(
SUBSTRING(Duration,
CASE WHEN HoursIndex > 0 THEN HoursIndex + 5
ELSE 0
END,
CASE WHEN HoursIndex > 0 THEN MinutesIndex - HoursIndex - 5
ELSE MinutesIndex
END
) As int) * 60
ELSE
0
END As M,
CASE WHEN SecondIndex > 0 THEN
CAST(
SUBSTRING(Duration,
CASE WHEN MinutesIndex > 0 THEN MinutesIndex + 7
ELSE 0
END,
CASE WHEN MinutesIndex > 0 THEN SecondIndex - MinutesIndex - 7
ELSE SecondIndex
END
) As int)
ELSE
0
END As S
FROM cte1
)
Now, update the NumberOfSeconds column:
UPDATE cte2
SET NumberOfSeconds = D + H + M + S
Verify the update results:
SELECT *
FROM #T
Results:
Duration NumberOfSeconds
---------------------------------------- ---------------
39 Seconds 39
2 Minutes 4 Seconds 124
1 Hours 7 Minutes 17 Seconds 4037
3 Days 9 Hour 8 Minutes 25 Seconds 292105