passing table identifiers IMHO clashes with SQL type system. passing table-typed arguments might work --- you still need one function per table signature, but no longer per table name; IMHO, there are plans to work on supporting something like that ... Stefan ----- Original Message -----
Martin,
Your answer to this question is useful but triggers a feature request that I'm very interested in for long :)
The major drawback of your workaround is that the name of the table to be limited is hard-coded inside the function. Which makes this solution impractical for real scenarios.
What is much missed - and would make your solution very useful in practice - is to be able to pass table identifiers as function parameters.
I could produce a long list of issues that would be solved by this ;) On 5 Nov 2014 17:24, "Martin Kersten" < Martin.Kersten@cwi.nl > wrote:
Hi
This recurring question has a simple solution in MonetDB for most of the cases considered. Simple rip out the subquery and encapsulate it in table producing function. The following example shows how:
-- select * from tables where id in (select id from tables limit 1); create function limited() returns table (id integer) begin return select id from tables order by id desc limit 1; end; select * from tables where id in (select * from limited());
regards, Martin
On 05/11/14 16:52, Martin Kersten wrote:
Hi
A possible workaround is to enclose the query in a table producing function.
regards, Martin
On 05/11/14 16:49, Leo Kotschenreuther wrote:
Hi,
I understand why Monetdb does’t support ORDER BY in subqueries.
An ORDER BY combined with a LIMIT does influence the size of the query result set. Is there a workaround to use such a query?
Here’s my use case: I’m working with the spatial extension and have a table filled with polygons. Now I want to know the ids of all polygons that intersect the polygon with the biggest area.
Is there a chance to answer this use case with only one query?
Regards Leo
On 27 Oct 2014, at 19:02, Martin Kersten < Martin.Kersten@cwi.nl > wrote:
Hi
ORDER BY (and LIMIT/OFFSET for that matter) only control the overall shape of the query result set. Hence, they are indeed not supported within subqueries in MonetDB.
See thread https://www.monetdb.org/ pipermail/users-list/2013- October/006861.html
regards, Martin
On 27/10/14 17:57, Kotschenreuther, Leo wrote:
Hi all,
I tried to use some more complex queries, they contained subqueries. I will shortly desrcibe the situation:
I have two tables (e.g. test and foo) and want to join them. Furthermore I want to preselect a subset of one of the two tables by adding some conditions (e.g. order the records by attribute c and only choosing the biggest one). A query could look like the this:
*sql>select * from test join (select * from foo order by c limit 1);* * * The result I receive is the following:
*syntax error, unexpected ORDER, expecting INTERSECT or EXCEPT or UNION or ')' in: "select * from test join (select * from foo order**”* * * On the other hand, I can run the subquery without the main query and I receive a valid result.
Is there a possibility to use subqueries with an ORDER BY statement without separating them into two independent queries?
Regards Leo
______________________________ _________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/ mailman/listinfo/users-list
______________________________ _________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/ mailman/listinfo/users-list
______________________________ _________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/ mailman/listinfo/users-list
______________________________ _________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/ mailman/listinfo/users-list ______________________________ _________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/ mailman/listinfo/users-list
_______________________________________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/mailman/listinfo/users-list
-- | Stefan.Manegold@CWI.nl | DB Architectures (DA) | | www.CWI.nl/~manegold/ | Science Park 123 (L321) | | +31 (0)20 592-4212 | 1098 XG Amsterdam (NL) |