SQL Server - Update column from data in the same table

Question

I have a table that looks something like this:

SetId ID Premium 
2012 5 Y 
2012 6 Y 
2013 5 N 
2013 6 N

I want to update the 2013 records with the premium values where the setid equals 2012.
So after the query it would look like this:

SetId ID Premium 
2012 5 Y
 2012 6 Y 
2013 5 Y 
2013 6 Y

Any help greatly appreciated

Answer 1

DECLARE @Tbl TABLE (
    SetId INT,
    Id INT, 
    Premium VARCHAR(1)
)
INSERT INTO @Tbl VALUES (2012, 5, 'Y')
INSERT INTO @Tbl VALUES (2012, 6, 'Y')
INSERT INTO @Tbl VALUES (2013, 5, 'N')
INSERT INTO @Tbl VALUES (2013, 6, 'N')
--Before Update
SELECT * FROM @Tbl 
--Something like this is what you need
UPDATE t 
SET t.Premium = t2.Premium 
FROM @Tbl t 
INNER JOIN @Tbl t2 ON t.Id = t2.Id 
WHERE t2.SetId = 2012 AND t.SetId = 2013
--After Update    
SELECT * FROM @Tbl