sql - plsql - 获取第一行 - 哪个更好？

Question

LV_id number;
Cursor CR_test Is
  select t.id
  from table1 t
  where t.foo = p_foo
  order by t.creation_date; 

Open CR_test;
Fetch CR_test
 Into LV_id;
Close CR_test;

或者这个:

select x.id
from(select t.id
     from table1 t
     where t.foo=p_foo
     order by t.creation_date) x
where rownum = 1

以上两者都产生了相似的结果，但我需要知道哪个更有效!

Answer 1

这是汤姆·凯特的口头禅:

You should do it in a single SQL statement if at all possible.
If you cannot do it in a single SQL Statement, then do it in PL/SQL.
If you cannot do it in PL/SQL, try a Java Stored Procedure.
If you cannot do it in Java, do it in a C external procedure.
If you cannot do it in a C external routine, you might want to seriously think about why it is you need to do it…

http://tkyte.blogspot.com/2006/10/slow-by-slow.html