Is it the best SQL?

Hi,

I wonder Oracle will tune SQL by itself?

For examples:
1. select * from (select * from a union select * from b) c

    where c.column_1 = 1
2. select * from a where column_1 = 1 union

    select * from b where column_1 = 1
I think method 2 should be faster if Oracle does not tune it, am I right?

Another case is:
1. select * from a, b

    where a.col_1 = b.col_1 and

               a.col_2 = 1
2. select * from a, b

    where a.col_2 = 1 and

               a.col_1 = b.col_1
Which one is faster? I guess case 2!?

BTW, is it possible to build a SQL(add a where cause condition, add a column, etc...) in runtime? (Am I dreaming?)

Thank in advance!

Kevin Received on Tue Apr 14 1998 - 06:28:25 CDT