Update Top 1 record in table sql server [duplicate]

Answer 1

UPDATE TX_Master_PCBA
SET TIMESTAMP2 = '2013-12-12 15:40:31.593',
G_FIELD='0000'
WHERE TIMESTAMP2 IN 
(
   SELECT TOP 1 TIMESTAMP2
   FROM TX_Master_PCBA WHERE SERIAL_NO='0500030309'
   ORDER BY TIMESTAMP2 DESC   -- You need to decide what column you want to sort on
)