MS SQL Azure – TSQL to name the age between dates in text

It is relatively easy to calculate the number of either years, months days hours or seconds between two dates using the native DATEDIFF built in function which comes with SQL.

e.g.

SELECT dbo.t001trees.pkid, 
dbo.t001trees.plantdate, 
DATEDIFF(Year, dbo.t001trees.plantdate, GETDATE()) as treeage 
from dbo.t001trees;

But here is a function that will spell it out into a string that reads something like
2 days
1 month 2 days
2 years 1 month 2 days

CREATE OR ALTER FUNCTION dbo.functionyearmonthday
(
@datefrom Date,
@dateto Date
)
RETURNS varchar(100)
as
BEGIN
DECLARE @date1 DATETIME, @date2 DATETIME, @result VARCHAR(100);
DECLARE @years INT, @months INT, @days INT;

SET @date1 = @datefrom
SET @date2 = @dateto

SELECT @years = DATEDIFF(yy, @date1, @date2)
IF DATEADD(yy, -@years, @date2) < @date1
SELECT @years = @years-1
SET @date2 = DATEADD(yy, -@years, @date2)

SELECT @months = DATEDIFF(mm, @date1, @date2)
IF DATEADD(mm, -@months, @date2) < @date1
SELECT @months=@months-1
SET @date2= DATEADD(mm, -@months, @date2)

SELECT @days=DATEDIFF(dd, @date1, @date2)
IF DATEADD(dd, -@days, @date2) < @date1
SELECT @days=@days-1
SET @date2= DATEADD(dd, -@days, @date2)

SELECT @result= ISNULL(CAST(NULLIF(@years,0) AS VARCHAR(10)) + ' years ','')
+ ISNULL(' ' + CAST(NULLIF(@months,0) AS VARCHAR(10)) + ' months ','')
+ ISNULL(' ' + CAST(NULLIF(@days,0) AS VARCHAR(10)) + ' days','')

RETURN @result;
END

And if you would like to call the function from another query here is an example

SELECT dbo.functionyearmonthday(dbo.t001trees.plantdate, GETDATE()) as treeage FROM dbo.t001trees

That is enough for most people but it can be expanded to include hours minutes seconds and milliseconds which could be useful if you need more precision it can be seen that the DATEDIFF native function is included extensively within this function.

CREATE OR ALTER FUNCTION dbo.functiontimeperiodmoreprecision
(
@datefrom Date,
@dateto Date
)
RETURNS varchar(100)
as
BEGIN
DECLARE @date1 DATETIME, @date2 DATETIME, @result VARCHAR(100);
DECLARE @years INT, @months INT, @days INT,
@hours INT, @minutes INT, @seconds INT, @milliseconds INT;

SET @date1 = @datefrom
SET @date2 = @dateto

SELECT @years = DATEDIFF(yy, @date1, @date2)
IF DATEADD(yy, -@years, @date2) < @date1
SELECT @years = @years-1
SET @date2 = DATEADD(yy, -@years, @date2)

SELECT @months = DATEDIFF(mm, @date1, @date2)
IF DATEADD(mm, -@months, @date2) < @date1
SELECT @months=@months-1
SET @date2= DATEADD(mm, -@months, @date2)

SELECT @days=DATEDIFF(dd, @date1, @date2)
IF DATEADD(dd, -@days, @date2) < @date1
SELECT @days=@days-1
SET @date2= DATEADD(dd, -@days, @date2)

SELECT @hours=DATEDIFF(hh, @date1, @date2)
IF DATEADD(hh, -@hours, @date2) < @date1
SELECT @hours=@hours-1
SET @date2= DATEADD(hh, -@hours, @date2)

SELECT @minutes=DATEDIFF(mi, @date1, @date2)
IF DATEADD(mi, -@minutes, @date2) < @date1
SELECT @minutes=@minutes-1
SET @date2= DATEADD(mi, -@minutes, @date2)

SELECT @seconds=DATEDIFF(s, @date1, @date2)
IF DATEADD(s, -@seconds, @date2) < @date1
SELECT @seconds=@seconds-1
SET @date2= DATEADD(s, -@seconds, @date2)

SELECT @milliseconds=DATEDIFF(ms, @date1, @date2)

SELECT @result= ISNULL(CAST(NULLIF(@years,0) AS VARCHAR(10)) + ' years,','')
+ ISNULL(' ' + CAST(NULLIF(@months,0) AS VARCHAR(10)) + ' months,','')
+ ISNULL(' ' + CAST(NULLIF(@days,0) AS VARCHAR(10)) + ' days,','')
+ ISNULL(' ' + CAST(NULLIF(@hours,0) AS VARCHAR(10)) + ' hours,','')
+ ISNULL(' ' + CAST(@minutes AS VARCHAR(10)) + ' minutes and','')
+ ISNULL(' ' + CAST(@seconds AS VARCHAR(10))
+ CASE
WHEN @milliseconds > 0
THEN '.' + CAST(@milliseconds AS VARCHAR(10))
ELSE ''
END
+ ' seconds','')

RETURN @result
END

Author: Mark

Mark Brooks a forty something individual working and living in and around Edinburgh