Creating date in SQL Server 2008

Question

Is there something similar to DATEFROMPARTS(year, month, day) in SQL Server 2008? I want to create a date using the current year and month, but my own day of the month. This needs to be done in one line in order to be used in a computed column formula.

For Example (I'm not sure if it works because I do not have SQL Server 2012):

DATEFROMPARTS(YEAR(GETDATE()), MONTH(GETDATE()), 3)

Is there a way to do this in SQL Server 2008?

DATEFROMPARTS Seems only available in SQL Server 2012 (link)

Answer 1

Using the 3 from your example, you could do this:

dateadd(dd, 3 -1, dateadd(mm, datediff(mm,0, current_timestamp), 0))

It works by finding the number of months since the epoch date, adding those months back to the epoch date, and then adding the desired number of days to that prior result. It sounds complicated, but it's built on what was the canonical way to truncate dates prior to the Date (not DateTime) type added to Sql Server 2008.

You're probably going to see other answers here suggesting building date strings. I urge you to avoid suggestions to use strings. Using strings is likely to be much slower, and there are some potential pitfalls with alternative date collations/formats.

Answer 2

You could use something like this to make your own datetime:

DECLARE @year INT = 2012
DECLARE @month INT = 12
DECLARE @day INT = 25

SELECT CAST(CONVERT(VARCHAR, @year) + '-' + CONVERT(VARCHAR, @month) + '-' + CONVERT(VARCHAR, @day)
 AS DATETIME)

Answer 3

CREATE FUNCTION  DATEFROMPARTS
(
    @year int,
    @month int,
    @day int
)
RETURNS datetime
AS
BEGIN

     declare @d datetime

     select @d =    CAST(CONVERT(VARCHAR, @year) + '-' + CONVERT(VARCHAR, @month) + '-' + CONVERT(VARCHAR, @day) AS DATETIME)
    RETURN  @d 

END
GO

Answer 4

CREATE FUNCTION  DATEFROMPARTS
(
    @year int,
    @month int,
    @day int
)
RETURNS datetime
AS
BEGIN

    declare 
    @sy varchar(max)
    ,@sm varchar(max)
    ,@sd varchar(max)
    ;

    set @sy = convert(varchar(max),@year);
    set @sm = (case when @month<10 then '0' else '' end) + 
    convert(varchar(max),@month);
    set @sd = (case when @day<10 then '0' else '' end) + 
    convert(varchar(max),@day);

    RETURN  convert(datetime, @sy + '-' + @sm + '-' + @sd + 'T00:00:00.000');
END