> On 18/11/2011 05:38, Vlad Khorsun wrote:
>>> On 16-11-2011 22:39, Frank Ingermann wrote:
>>>> ...but it leads to an endless loop/recursion (using latest Fb3 beta)
>>>> :-(
>>>>
>>> Before decide what to do, I'd like to hear Vlad about the error
>>> isc_dsql_cte_wrong_clause, which, for example, happens if a recursive
>>> query has a GROUP BY.
>>>
>>> Why is it not allowed?
>> Because standard prohibits any kind of aggregates in recursive CTE
>> members.
>>
> Could you point me where is this described? I don't found it.
Its hidded very well :) Seems i found it:
7.13 <query expression>
Syntax Rules
...
2) If <with clause> is specified, then:
...
g) For a potentially recursive <with list> WL with n elements, and for i
ranging from 1 (one) to n, let WLEi
be the i-th <with list element> of WL, let WQNi be the <query name>
immediately contained in WLEi,
let WQEi be the <query expression> simply contained in WLEi, let WQTi
be the table defined by WQEi,
and let QNDG be the query name dependency graph of WL.
...
iii) For each WLEi, for i ranging from 1 (one) to n, and for each WQNj
that belongs to the stratum of WQEi:
...
4) WQEi shall not contain a <query specification> QS such that:
...
B) QS immediately contains a <select list> SL or TE immediately
contains a <having clause>
HC and SL or TE contain a <set function specification>.
Where
6.9 <set function specification>
<set function specification> ::=
<aggregate function>
| <grouping operation>
Regards,
Vlad
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