that looks like an accidental cross join to me.
it explicitly says UPDATE DRPDATA, but since the FROM has the table name as being aliased,and the unaliased table is not referenced anywhere else, there is an implied cross join like this:
UPDATE DRPDATA
SET ....
FROM DRPDATA A ,DRPDATA
the UPDATE should be UPDATE ALIASNAME explicitly.
-- ADD average FTE Hrs for the Week based table with daily data
UPDATE A
SET A.FTEHrsAVG =
(
SELECTAVG(B.FTEHrs)
FROMDRPDATA B
WHEREA.MWID = B.MWID
AND
DATEPART(ISO_WEEK,A.BEGINDATUM)= DATEPART(ISO_WEEK,B.BEGINDATUM)
AND
A.[Org eenheid code] = B.[Org eenheid code]
AND
B.FlexVast = 'VAST'
GROUP BYB.MWID,b.[Org eenheid code], DATEPART(ISO_WEEK,B.BEGINDATUM)
)
FROMDRPDATA A;
Lowell