Date serial in SQL?

Question

How can I convert a day [1-31] and a month [1-12] and a year (all int), to a date serial IN SQL (without converting to varchar)?

Answer 1

Zero is 01 jan 1900 in SQL, so you can use this:

DATEADD(day, @dayval-1,
     DATEADD(month, @monthval-1,
         DATEADD(year, @yearval-1900, 0)
     )
)

Edit, Feb 2018

As the other answer says, since SQL Server 2012 (released after the original answer) we can use DATEFROMPARTS

 SELECT DATEFROMPARTS (@yearval, @monthval, @dayval)

Answer 2

A few functions have been added in SQL Server 2012 which will allow you to do this with DATEFROMPARTS, DATETIMEFROMPARTS and TIMEFROMPARTS amongst others.

Example:

SELECT DATEFROMPARTS(2018,2,1) -- returns 2018-02-01