How to use DATEDIFF to return year, month and day?

Question

How can I use DATEDIFF to return the difference between two dates in years, months and days in SQL Server 2005

DATEDIFF (date , dat         


        

Answer 1

Using ParseName

DECLARE
  @ReportBeginDate DATE

SET @ReportBeginDate='2015-01-01';

IF OBJECT_ID('TEMPDB..#tmp_ymd') IS NOT NULL
BEGIN
DROP TABLE #tmp_ymd;
END;

select
cast(cast(datediff(mm,@ReportBeginDate,getdate()) as decimal (10,2))/12 as decimal(10,2)) as YearMonthDec
,cast(datediff(dd,@ReportBeginDate,getdate()) as decimal (10,2)) as DayDec
into #tmp_ymd

select
YearMonthDec
,cast(parsename(YearMonthDec,2) as decimal (10,0)) as yearnum
,cast(cast(parsename(YearMonthDec,1) as decimal (10,0))/100*(12) as numeric) as monthnum
,case when YearMonthDec>=1 then datediff(dd,CONVERT(VARCHAR(25),DATEADD(dd,-(DAY(getdate())-1),getdate()),101),getdate()) else DayDec end as daynum

from #tmp_ymd

Answer 2

TL;DR approximates years & months without having to create a function.

---

I found this question searching for "get years months from datediff". I was looking for something a bit quicker (and yeah, probably dirtier) than the above function-creating solutions.

I came up with the following in-line sql which approximates the years and months. Sufficient for my own purposes, which is getting a count of events grouped by user's rough age at the time.

select cast(datediff(event_datetime, dateofbirth)/365.25 as unsigned) as years, 
       cast((mod(datediff(event_datetime, dateofbirth),365.25))/30.4375 as unsigned) as months
from tablename
;

Answer 3

Check this page... http://www.sqlteam.com/article/datediff-function-demystified

Create this functions:

CREATE FUNCTION dbo.fnYearsApart
(
        @FromDate DATETIME,
        @ToDate DATETIME
)
RETURNS INT
AS
BEGIN
        RETURN  CASE
                       WHEN @FromDate > @ToDate THEN NULL
                       WHEN DATEPART(day, @FromDate) > DATEPART(day, @ToDate) THEN DATEDIFF(month, @FromDate, @ToDate) - 1
                       ELSE DATEDIFF(month, @FromDate, @ToDate)
               END / 12
END

and

CREATE FUNCTION dbo.fnMonthsApart
(
        @FromDate DATETIME,
        @ToDate DATETIME
)
RETURNS INT
AS
BEGIN
        RETURN  CASE
                       WHEN @FromDate > @ToDate THEN NULL
                       WHEN DATEPART(day, @FromDate) > DATEPART(day, @ToDate) THEN DATEDIFF(month, @FromDate, @ToDate) - 1
                       ELSE DATEDIFF(month, @FromDate, @ToDate)
               END
END

and finally

ALTER FUNCTION [dbo].[gatYMD](@dstart VARCHAR(50), @dend VARCHAR(50))
RETURNS VARCHAR(50) AS
BEGIN
    DECLARE @yy INT
    DECLARE @mm INT
    DECLARE @dd INT
    DECLARE @getmm INT
    DECLARE @getdd INT

    SET @yy = dbo.fnYearsApart(@dstart, @dend)  --DATEDIFF(yy, @dstart, @dend)
    SET @mm = dbo.fnMonthsApart(@dstart, @dend) --DATEDIFF(mm, @dstart, @dend)
    SET @dd = DATEDIFF(dd, @dstart, @dend)
    SET @getmm = ABS(DATEDIFF(mm, DATEADD(yy, @yy, @dstart), @dend))
    SET @getdd = ABS(DATEDIFF(dd, DATEADD(mm, DATEDIFF(mm, DATEADD(yy, @yy, @dstart), @dend), DATEADD(yy, @yy, @dstart)), @dend))

    RETURN (
      Convert(varchar(10),@yy) + ' años, ' + Convert(varchar(10),@getmm) + ' meses, '  + Convert(varchar(10),@getdd) + ' días'
    )
END

Greats!