SQL Server – Update column from data in the same table

It’s not clear which 2012 value you want to use to update which 2013 value, i’ve assumed that the ID should be the same.

Full example using table variables that you can test yourself in management studio.

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