better approach: case or join

from id extracting name from several tables.  which is generally the
better approach?

select case when tab_tla='usr' then (select name from users where ... )      case when tab_tla='con' then (select title
fromcontents where
 
...)
end    as name;

as versus

select  name
from    users
where   tab_tla='usr' and ...       join
select  title
from    contents
where   tab_tla='con' and ...

I assume the former since the optimizer does not examine whether the
entire where clause might be false before executing the query.

thanks,
chester


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