update on two inner joins vs update with one select and one inner join code example

Example 1: how to add where command in update comand with joins

UPDATE A
SET foo = B.bar
FROM TableA A
JOIN TableB B
    ON A.col1 = B.colx
WHERE ...

Example 2: joins in update query

update a
join b 
on a.a_id=b.b_id 
set b.is_active = 1 
where ....;