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From Riyafa Abdul Hameed <riyafa...@cse.mrt.ac.lk>
Subject Re: How to write SQL 92 aggregate function?
Date Fri, 04 Aug 2017 10:58:34 GMT
Hi,

After learning about sql92 and sql++, I thinks that should be the expected
behavior. But I would like to evaluate the same behavior using sql++, can
someone help me with a query because I lack full knowledge of sql++.

Thanks.
Riyafa

On 4 August 2017 at 12:10, Riyafa Abdul Hameed <riyafa@apache.org> wrote:

> Dear all,
>
> With Preston's help I managed to implement an aggregate function that
> works on arrays:
> st_union([st_make_point(1.0,1.0),st_make_point(1.0,2.0)]);
> But this does not work when used in an sqlpp expression:
> SELECT st_union(gbu) FROM [st_make_point(1.0,1.0),st_make_point(1.0,2.0)]
> as gbu;
>
> The error thrown is:
>
> ASX0002: Type mismatch: function scan-collection expects its 1st input parameter to be
type array or multiset, but the actual input type is geometry [TypeMismatchException]
>
> I think it's because the function has not been implemented as an SQL 92
> function. I would like to know how to do this?
>
> This error is thrown when count is used in the following manner:
> SELECT array_count(gbu) FROM [1,2,3] as gbu;
>
> It is not thrown when used in the following manner:
> SELECT count(gbu) FROM [1,2,3] as gbu;
>
> When count is used in the following manner:
>
> count([1,2,3]);
>
> the following error is thrown:
>
> count is a SQL-92 aggregate function. The SQL++ core aggregate function
> array_count could potentially express the intent. [CompilationException]
>
> I would like to know how I could have st_union also as a SQL-92 function.
> My changes are in the following branch:
> https://github.com/riyafa/asterixdb/tree/geometry
>
>
>
>


-- 
Riyafa Abdul Hameed
Undergraduate, University of Moratuwa

Email: riyafa.12@cse.mrt.ac.lk
Website: https://riyafa.wordpress.com/ <http://riyafa.wordpress.com/>
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