Oracle FAQ | Your Portal to the Oracle Knowledge Grid |
Home -> Community -> Usenet -> c.d.o.misc -> Re: SQL Tuning question
Another question. I'm trying to find out the most efficient way to
join multiple tables. Take a situation in which you are joining
multiple tables on the same field. Is it better to join table1 to
table2 then table2 to table3 like below:
select TABLE1.partno from TABLE1, TABLE2, TABLE3 where table1.partno = table2.partno and
table2.partno = table3.partno;
Or is it better to join all from the table1 field, like below: select TABLE1.partno from TABLE1, TABLE2, TABLE3 where table1.partno = table2.partno and
table1.partno = table3.partno;
I did a quick explain plan and scenario #2 showed a lower cost but I don't know if that's because of my data or not. I saw a book example which used scenario #1. Can I make a hard and fast rule on this type of thing, or does it depend on the data, the driving table, etc?
Thanks,
Dan
Received on Thu Oct 20 2005 - 15:15:12 CDT