Another set based solution, this time using the good old Tally table[/url]. ((c) Jeff Moden et al. 19xx-2009)

SELECT TOP 1

DATEADD(dd,N-1,GETDATE())

FROM

Tally

WHERE

n < 366 --== One years worth of days

AND

DAY(DATEADD(dd,N-1,GETDATE())) = 13

AND

--==

--== Using @@DATEFIRST and the modulus operator we don't need to change or

--== assume anything about the current DATEFIRST setting

--==

(@@DATEFIRST + DATEPART(dw,DATEADD(dd,N-1,GETDATE()))) %7 = 6

ORDER BY

N

The execution plan for this indicates 100% of the query is spent doing a clustered index seek (nice!). That's if you build your tally table with a clustered index of course, as demonstrated in Jeff's tally table article.

And, as I indicated in the comments, you don't need to mess about with the DATEFIRST setting.