Обсуждение: joins

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joins

От
Jodi Kanter
Дата:
Can anyone tell me if there is any real difference between the two different ways to create tables joins?
 
select field1, field2 from table1 join table2 using (field3)
 
vs.
 
select field1, field2 from table1, table 2 where table1.field3=table2.field3
 
Thanks
Jodi
 
 

_______________________________
Jodi L Kanter
BioInformatics Database Administrator
University of Virginia
(434) 924-2846
jkanter@virginia.edu

 

 

 

Re: joins

От
Bruno Wolff III
Дата:
On Mon, Nov 04, 2002 at 14:37:42 -0500,
  Jodi Kanter <jkanter@virginia.edu> wrote:
> Can anyone tell me if there is any real difference between the two different ways to create tables joins?
>
> select field1, field2 from table1 join table2 using (field3)
>
> vs.
>
> select field1, field2 from table1, table 2 where table1.field3=table2.field3

The first form fixes the join order while the second allows the planner to
choose what order to do the joins in. For just two tables this doesn't
make a difference.