S-SQL and nested joins -- correct version
Marijn Haverbeke
marijnh at gmail.com
Fri Feb 28 08:00:13 UTC 2014
Hi Eli,
I don't believe this is supported right now. Take a look at the code
that parses joins, if you want to be sure.
Best,
Marijn
On Fri, Feb 28, 2014 at 2:13 AM, Eli Naeher <enaeher at gmail.com> wrote:
> Hello,
>
> My apologies, I sent my previous email by mistake before I'd finished
> composing it. Here is the completed email:
>
> Is there an S-SQL expression which will produce nested join expressions like
> this one:
>
> select * from table_1
> inner join table_2
> inner join table_3 on table_2.c = table_3.d
> on table_1.a = test_2.b;
>
> (This form is described in section 7.2.1.1 of the Postgres documentation,
> which says, "Joins of all types can be chained together or nested: either or
> both T1 and T2 can be joined tables.")
>
> I know I can do this:
>
> (:select '* :from 'table-1
> :inner-join 'table-2 :on (:= 'table-1.a 'table-2.b)
> :inner-join 'table-3 :on (:= 'table-2.c 'table-3.d))
>
> which produces a chained join expression:
>
> (SELECT * FROM table_1
> INNER JOIN table_2 ON (table_1.a = table_2.b) INNER JOIN table_3 ON
> (table_2.c = table_3.d))
>
> However, these chained join expressions behave differently than nested ones
> when mixing different types of joins (inner with outer, etc.), and I need
> the behavior of the nested expression. I tried this:
>
> (:select '* :from 'table-1
> :inner-join 'table-2
> :inner-join 'table-3 :on (:= 'table-2.c 'table-3.d)
> :on (:= 'table-1.a 'table-2.b))
>
> But it produces the error "Incorrect join form in select."
>
> Am I missing the correct syntax, or is this unsupported right now?
>
> Thank you,
> -Eli
>
>
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