Best way to convert DateTime to "n Hours Ago" in SQL - sql

Question

I wrote a SQL function to convert a datetime value in SQL to a friendlier "n Hours Ago" or "n Days Ago" etc type of message. And I was wondering if there was a better way to do it.
(Yes I know "don't do it in SQL" but for design reasons I have to do it this way).
Here is the function I've written:
CREATE FUNCTION dbo.GetFriendlyDateTimeValue
(
#CompareDate DateTime
)
RETURNS nvarchar(48)
AS
BEGIN
DECLARE #Now DateTime
DECLARE #Hours int
DECLARE #Suff nvarchar(256)
DECLARE #Found bit
SET #Found = 0
SET #Now = getDate()
SET #Hours = DATEDIFF(MI, #CompareDate, #Now)/60
IF #Hours <= 1
BEGIN
SET #Suff = 'Just Now'
SET #Found = 1
RETURN #Suff
END
IF #Hours < 24
BEGIN
SET #Suff = ' Hours Ago'
SET #Found = 1
END
IF #Hours >= 8760 AND #Found = 0
BEGIN
SET #Hours = #Hours / 8760
SET #Suff = ' Years Ago'
SET #Found = 1
END
IF #Hours >= 720 AND #Found = 0
BEGIN
SET #Hours = #Hours / 720
SET #Suff = ' Months Ago'
SET #Found = 1
END
IF #Hours >= 168 AND #Found = 0
BEGIN
SET #Hours = #Hours / 168
SET #Suff = ' Weeks Ago'
SET #Found = 1
END
IF #Hours >= 24 AND #Found = 0
BEGIN
SET #Hours = #Hours / 24
SET #Suff = ' Days Ago'
SET #Found = 1
END
RETURN Convert(nvarchar, #Hours) + #Suff
END

Answer 1

As you say, I probably wouldn't do it in SQL, but as a thought exercise have a MySQL implementation:
CASE
WHEN compare_date between date_sub(now(), INTERVAL 60 minute) and now()
THEN concat(minute(TIMEDIFF(now(), compare_date)), ' minutes ago')
WHEN datediff(now(), compare_date) = 1
THEN 'Yesterday'
WHEN compare_date between date_sub(now(), INTERVAL 24 hour) and now()
THEN concat(hour(TIMEDIFF(NOW(), compare_date)), ' hours ago')
ELSE concat(datediff(now(), compare_date),' days ago')
END
Based on a similar sample seen on the MySQL Date and Time manual pages

Answer 2

In Oracle:
select
CC.MOD_DATETIME,
'Last modified ' ||
case when (sysdate - cc.mod_datetime) < 1
then round((sysdate - CC.MOD_DATETIME)*24) || ' hours ago'
when (sysdate - CC.MOD_DATETIME) between 1 and 7
then round(sysdate-CC.MOD_DATETIME) || ' days ago'
when (sysdate - CC.MOD_DATETIME) between 8 and 365
then round((sysdate - CC.MOD_DATETIME) / 7) || ' weeks ago'
when (sysdate - CC.MOD_DATETIME) > 365
then round((sysdate - CC.MOD_DATETIME) / 365) || ' years ago'
end
from
customer_catalog CC

Answer 3

My attempt - this is for MS SQL. It supports 'ago' and 'from now', pluralization and it doesn't use rounding or datediff, but truncation -- datediff gives 1 month diff between 8/30 and 9/1 which is probably not what you want. Rounding gives 1 month diff between 9/1 and 9/16. Again, probably not what you want.
CREATE FUNCTION dbo.GetFriendlyDateTimeValue( #CompareDate DATETIME ) RETURNS NVARCHAR(48) AS BEGIN
declare #s nvarchar(48)
set #s='Now'
select top 1 #s=convert(nvarchar,abs(n))+' '+s+case when abs(n)>1 then 's' else '' end+case when n>0 then ' ago' else ' from now' end from (
select convert(int,(convert(float,(getdate()-#comparedate))*n)) as n, s from (
select 1/365 as n, 'Year' as s union all
select 1/30, 'Month' union all
select 1, 'Day' union all
select 7, 'Week' union all
select 24, 'Hour' union all
select 24*60, 'Minute' union all
select 24*60*60, 'Second'
) k
) j where abs(n)>0 order by abs(n)
return #s
END

Answer 4

Your code looks functional. As for a better way, that is going to get subjective. You might want to check out this page as it deals with time spans in SQL.

Answer 5

How about this? You could expand this pattern to do "years" messages, and you could put in a check for "1 day" or "1 hour" so it wouldn't say "1 days ago"...
I like the CASE statement in SQL.
drop function dbo.time_diff_message
GO
create function dbo.time_diff_message (
#input_date datetime
)
returns varchar(200)
as
begin
declare #msg varchar(200)
declare #hourdiff int
set #hourdiff = datediff(hour, #input_date, getdate())
set #msg = case when #hourdiff < 0 then ' from now' else ' ago' end
set #hourdiff = abs(#hourdiff)
set #msg = case when #hourdiff > 24 then convert(varchar, #hourdiff/24) + ' days' + #msg
else convert(varchar, #hourdiff) + ' hours' + #msg
end
return #msg
end
GO
select dbo.time_diff_message('Dec 7 1941')

Answer 6

Thanks for the various code posted above.
As Hafthor pointed out there are limitations of the original code to do with rounding. I also found that some of the results his code kicked out didn't match with what I'd expect e.g. Friday afternoon -> Monday morning would show as '2 days ago'. I think we'd all call that 3 days ago, even though 3 complete 24 hour periods haven't elapsed.
So I've amended the code (this is MS SQL). Disclaimer: I am a novice TSQL coder so this is quite hacky, but works!!
I've done some overrides - e.g. anything up to 2 weeks is expressed in days. Anything over that up to 2 months is expressed in weeks. Anything over that is in months etc. Just seemed like the intuitive way to express it.
CREATE FUNCTION [dbo].[GetFriendlyDateTimeValue]( #CompareDate DATETIME ) RETURNS NVARCHAR(48) AS BEGIN
declare #s nvarchar(48)
set #s='Now'
select top 1 #s=convert(nvarchar,abs(n))+' '+s+case when abs(n)>1 then 's' else '' end+case when n>0 then ' ago' else ' from now' end from (
select convert(int,(convert(float,(getdate()-#comparedate))*n)) as n, s from (
select 1/365 as n, 'year' as s union all
select 1/30, 'month' union all
select 1/7, 'week' union all
select 1, 'day' union all
select 24, 'hour' union all
select 24*60, 'minute' union all
select 24*60*60, 'second'
) k
) j where abs(n)>0 order by abs(n)
if #s like '%days%'
BEGIN
-- if over 2 months ago then express in months
IF convert(nvarchar,DATEDIFF(MM, #CompareDate, GETDATE())) >= 2
BEGIN
select #s = convert(nvarchar,DATEDIFF(MM, #CompareDate, GETDATE())) + ' months ago'
END
-- if over 2 weeks ago then express in weeks, otherwise express as days
ELSE IF convert(nvarchar,DATEDIFF(DD, #CompareDate, GETDATE())) >= 14
BEGIN
select #s = convert(nvarchar,DATEDIFF(WK, #CompareDate, GETDATE())) + ' weeks ago'
END
ELSE
select #s = convert(nvarchar,DATEDIFF(DD, #CompareDate, GETDATE())) + ' days ago'
END
return #s
END

Answer 7

The posts above gave me some good ideas so here is another function for anyone using SQL Server 2012.
CREATE FUNCTION [dbo].[FN_TIME_ELAPSED]
(
#TIMESTAMP DATETIME
)
RETURNS VARCHAR(50)
AS
BEGIN
RETURN
(
SELECT TIME_ELAPSED =
CASE
WHEN #TIMESTAMP IS NULL THEN NULL
WHEN MINUTES_AGO < 60 THEN CONCAT(MINUTES_AGO, ' minutes ago')
WHEN HOURS_AGO < 24 THEN CONCAT(HOURS_AGO, ' hours ago')
WHEN DAYS_AGO < 365 THEN CONCAT(DAYS_AGO, ' days ago')
ELSE CONCAT(YEARS_AGO, ' years ago') END
FROM ( SELECT MINUTES_AGO = DATEDIFF(MINUTE, #TIMESTAMP, GETDATE()) ) TIMESPAN_MIN
CROSS APPLY ( SELECT HOURS_AGO = DATEDIFF(HOUR, #TIMESTAMP, GETDATE()) ) TIMESPAN_HOUR
CROSS APPLY ( SELECT DAYS_AGO = DATEDIFF(DAY, #TIMESTAMP, GETDATE()) ) TIMESPAN_DAY
CROSS APPLY ( SELECT YEARS_AGO = DATEDIFF(YEAR, #TIMESTAMP, GETDATE()) ) TIMESPAN_YEAR
)
END
GO
And the implementation:
SELECT TIME_ELAPSED = DBO.FN_TIME_ELAPSED(AUDIT_TIMESTAMP)
FROM SOME_AUDIT_TABLE

Answer 8

CASE WHEN datediff(SECOND,OM.OrderDate,GETDATE()) < 60 THEN
CONVERT(NVARCHAR(MAX),datediff(SECOND,OM.OrderDate,GETDATE())) +' seconds ago'
WHEN datediff(MINUTE,OM.OrderDate,GETDATE()) < 60 THEN
CONVERT(NVARCHAR(MAX),datediff(MINUTE,OM.OrderDate,GETDATE())) +' minutes ago'
WHEN datediff(HOUR,OM.OrderDate,GETDATE()) < 24 THEN
CONVERT(NVARCHAR(MAX),datediff(HOUR,OM.OrderDate,GETDATE())) +' hours ago'
WHEN datediff(DAY,OM.OrderDate,GETDATE()) < 8 THEN
CONVERT(NVARCHAR(MAX),datediff(DAY,OM.OrderDate,GETDATE())) +' Days ago'
ELSE FORMAT(OM.OrderDate,'dd/MM/yyyy hh:mm tt') END AS TimeStamp