Worked for me thanks!!

Sorry, after reviewing mickyT's code and results i realize the dates should be "contiguous" if i'm understanding correctly.(in which mickyT's does just that). Just wanted to post an update to...

I think this may work as well...not 100%

UPDATE target_table

SET to_Date = (T2.from_date-1)

FROM target_table T1

LEFT JOIN source_table T2 ON T1.Uarn = T2.Uarn

WHERE t1.to_Date IS NULL

INSERT target_table

SELECT DISTINCT...

For the basics ....

http://www.w3schools.com/sql/