sql query to only display the highest value code example

Example 1: get row from max

SELECT * 
FROM t1 WHERE (id,rev) IN 
( SELECT id, MAX(rev)
  FROM t1
  GROUP BY id
)

Example 2: sql set max value in column

ALTER TABLE dbo.mytable ADD CONSTRAINT CK_HAPPINESS_MAX CHECK (PokemonHappiness <= 10000)