Subject Re: [IBO] Problem with TIBOQuery
Author Helen Borrie
At 08:51 PM 1/02/2005 -0700, you wrote:

>Hello Helen,
>Did some more digging and found out that
>IB_Componets->function TIB_Dataset.SysGetCursorRecordCount: longint;
>already converts a RecordCount call for
>'select * from table where such = true'
>'select count(*) from table where such = true'
>at IB_Components->MakeCountSQL( ServerSQL, CountSQL );
>and uses this modified select to get the proper count as fast as possible :)
>This conversion is done in IB_Parse->MakeCountSQL
>Elas, in the case of a 'select * from table union select * from table2' it
>converts it to
>'select count(*) from table1 union select * from table2' , which of course
>in that at first rather obscure parameter count mismatch error.


>By simply adding the following two statements before the last statement of
>this routine
> ep := getLitSafeStrPos( 'UNION', AnsiUpperCase( CountSQL ), 1 );
> if ep > 1 then CountSQL := Copy(CountSQL,1,ep-1);
>CountSQL := Trim( CountSQL );
>RecordCount now only returns the count of the record of the first select and
>raise an exception.

Really useful, right?

>However, I think with a little more work IB_Componets->function
>TIB_Dataset.SysGetCursorRecordCount can be altered to split and
>summerize the count(*) of the various unionized selects and thus returns
>a momentarily correct RecordCount across all unions
>What do you think ?

Not useful at all. With UNION sets, the recordcount is not the same as the
sum of recordcounts of the contributing selects - unless you specify UNION
ALL (which you rarely do, in practice). You've literally got to fetch the
entire set and count the output rows.

...since you asked...