SQL update in one statement instead of two

Question

Is it possible to do the following in 1 statement instead of 2. I need to set the isActive flag for one id and set all the others to false. Im using postgres DB.

tblNames 
------------------------
id,name,isActive
1,'n1',true
2,'n2',false
3,'n3',false
4,'n4',false

update tblnames
set isActive = true 
where id = 4

update tblnames
set isActive = false 
where id != 4

Answer 1

Does that work?

update tblnames
set isActive = (id = 4)

In case it doesn't (I don't know Postgres syntax well enough), this will surely work:

update tblnames
set isActive case id when 4 then true else false end