JOIN two tables question

I need to UPDATE a field in a table.  tbl2015 will have data that is NOT in tbl2014.  Those rows that are NOT IN tbl2014 I want to SET ComparePriorYr = '2'.  I am having trouble with my query.  Here is what I have so far.

UPDATE tblStockCertInfo_2015
SET ComparePriorYr = '2'

FROM tblStockCertInfo_2015 tbl2015
 LEFT JOIN tblStockCertInfo_2014  tbl2014 ON tbl2014.InfoUniqueKey = tbl2015.InfoUniqueKey

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What type of JOIN do I use to get only the data that is in tbl2015 and NOT IN tbl2014?
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Brendt HessSenior DBACommented:
Your LEFT JOIN is correct. What you need is a WHERE clause that filters on the tbl2014.InfoUniqueKey field, like this one:

WHERE tbl2014.InfoUniqueKey IS NULL

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Qlemo"Batchelor", Developer and EE Topic AdvisorCommented:
Use the alias in UPDATE, if defined:
UPDATE tbl2015
SET ComparePriorYr = '2'
FROM tblStockCertInfo_2015 tbl2015
LEFT JOIN tblStockCertInfo_2014 tbl2014
ON bl2014.InfoUniqueKey = tbl2015.InfoUniqueKey
WHERE bl2014.InfoUniqueKey IS NULL

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huerita37Author Commented:
I gave most of the points to bhess1 since he was the first and so quick.  I did want to award some points to Qlemo because he responded with a good solution as well.
Jim HornMicrosoft SQL Server Data DudeCommented:
>tbl2015 will have data that is NOT in tbl2014.
In addition to the above correct comments, to better understand this concept do an search for 'sql joins', and you'll see some lovely pictures that illustrate this.  Since they're all copyrighted we can't just post them here.
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