Creating an Inner Join with Outer Join-Style Syntax

I am studying the e-learning course for the SAS Advanced certification, and
in a lesson it says about Creating an Inner Join with Outer Join-Style
Syntax :
------

"General form, SELECT statement for inner join (alternate syntax):

SELECT column-1<,...column-n>
FROM table-1 | view-1
INNER JOIN table-2 | view-2
ON join-condition(s)
<other clauses>;

An inner join that uses this syntax can be performed on only two tables or
views at a time. When an inner join uses the syntax presented earlier, up to
32 tables or views can be combined at once. In-line views are covered later
in this lesson."

-----

I wonder what this means - "only two tables at a time". In the code example
below, *three* tables are joined together using the inner join syntax:

data one;
input x1 $ 1
a $ 3;
datalines;
1 a
2 b
4 d
;
data two;
input x2 $ 1
b $ 3;
datalines;
2 x
3 y
5 v
;
data three;
input x3 $ 1
c $ 3;
datalines;
2 r
5 s
;
proc sql;
create table inner_join as
select *
from one
inner join two
on one.x1 = two.x2
inner join three
on two.x2 = three.x3;
quit;

The join table could as well have been written:
proc sql;
create table equijoin as
select *
from one, two, three
where one.x1 = two.x2
and one.x1 = three.x3;
quit;

It is not evident to me what the author of the e-learning course means by
the quotation above.


Regard
Rune

Rune Runnestø wrote with clarity:
....snip...
> It is not evident to me what the author of the e-learning course
> means by the quotation above.

Me either. You should contact the course administrator and report the
section as having mistatements or needing additional narrative.

--
Richard A. DeVenezia

Rune Runnestø wrote:
> I am studying the e-learning course for the SAS Advanced certification, and
> in a lesson it says about Creating an Inner Join with Outer Join-Style
> Syntax :
> ------
>
> "General form, SELECT statement for inner join (alternate syntax):
>
> SELECT column-1<,...column-n>
> FROM table-1 | view-1
> INNER JOIN table-2 | view-2
> ON join-condition(s)
> <other clauses>;
>
> An inner join that uses this syntax can be performed on only two tables or
> views at a time. When an inner join uses the syntax presented earlier, upto
> 32 tables or views can be combined at once. In-line views are covered later
> in this lesson."
>
> -----
>
> I wonder what this means - "only two tables at a time". In the code example
> below, *three* tables are joined together using the inner join syntax:
>
> data one;
> input x1 $ 1
> a $ 3;
> datalines;
> 1 a
> 2 b
> 4 d
> ;
> data two;
> input x2 $ 1
> b $ 3;
> datalines;
> 2 x
> 3 y
> 5 v
> ;
> data three;
> input x3 $ 1
> c $ 3;
> datalines;
> 2 r
> 5 s
> ;
> proc sql;
> create table inner_join as
> select *
> from one
> inner join two
> on one.x1 = two.x2
> inner join three
> on two.x2 = three.x3;
> quit;
>
> The join table could as well have been written:
> proc sql;
> create table equijoin as
> select *
> from one, two, three
> where one.x1 = two.x2
> and one.x1 = three.x3;
> quit;
>
> It is not evident to me what the author of the e-learning course means by
> the quotation above.
>
>
> Regard
> Rune

Yeah, it works for me in v9. And full joins instead of inner joins work
too. But I have a vague recollection of similar >2 table joins not
working in some SQL code I tried to write at some point in my life
(without parentheses, etc.) ...... Might be a versioning issue, or
something not supported in all versions of SQL? Seems to work OK on our
DB2, though.