In trying to combine the two subqueries into one, I got this far, but have encountered the error messages:

The multi-part identifier "a.IDNumber" could not be bound.

The multi-part identifier "a.MarketDate" could not be bound.

UPDATE a

SET StDev_OH_30Day=T.StDev_OHdiff

, StDev_OL_30Day=T.StDev_OLdiff

FROM myTable,

(SELECT STDEV(b.OHdiff) AS StDev_OHdiff

, STDEV(b.OLdiff) AS StDev_OLdiff

FROM myTable b

WHERE b.IDNumber = a.IDNumber

AND b.MarketDate < a.MarketDate

AND b.MarketDate > a.MarketDate-31 ) AS T

WHERE

a.MarketDate BETWEEN @lastUpdate+.1 AND @updateThrough

AND a.IDNumber BETWEEN @minIDNumber AND @maxIDNumber

If anyone's got any ideas or suggestions, I would really appreciate it.

Thanks!