update table with différents conditions

I want to make an update in my Student table ( colums : Id, name , age UpdatedDate) according two conditions:

@id = 10
UPDATE Student SET Id = @id, UpdatedDate = GETDATE() WHERE Name = "David"
IF age is NULL AND @id = 10 UPDATE Student SET Id = @id, UpdatedDate = GETDATE(), age = 22 WHERE Name = "David"

how can I do this update in a more optimal way please ?
the two updates are similar except the difference of a column that we only update if a condition is verified
thank you

>Solution :

You can try to UPDATE by CASE WHEN expression, Making your expectation condition then return result to UPDATE, otherwise use original value in ELSE do nothing.

UPDATE Student 
SET Id = @id, 
    UpdatedDate = GETDATE(),
    age = (CASE WHEN age is NULL AND @id = 10 THEN 22 ELSE age END)
WHERE Name = 'David'

sqlfiddle