Thanks all, the problem has been solved as Helen mentioned.

Best Regards,
Eric Leung,

--- In IBObjects@y..., "Helen Borrie (TeamIBO)" <helebor@t...> wrote:
> At 02:18 AM 15-05-02 +0000, you wrote:
> >I have problem in using the following SQL in IBO
> >
> >I have a table with structure
> >F1 F2 Q1
> >1 1 10
> >1 2 20
> >1 3 40
> >2 1 80
> >2 2 160
> >(F1,F2) is the primary key of the table
> >
> >and would like to get the result table with accumulated quantity Q2 of
> >Q1 as below:
> >F1 F2 Q1 Q2
> >1 1 10 10
> >1 2 20 30
> >1 3 40 70
> >2 1 80 80
> >2 2 160 240
> >
> >So I use following SQL
> >select F1, F2, Q1,
> >(select sum(Q1) from MyTable where F1 = a.F1
> >and F2 <= a.F2) as Q2
> >from MyTable a
> >order by F1, F2
> >
> >I was using with IB_SQL.exe (version 4.2Ha) in win98, Firebird 1.0 for
> >testing.
> >
> >But I got the following errors message:
> >ISC ERROR CODE:335544569
> >
> >ISC ERROR MESSAGE:
> >Dynamic SQL Error
> >SQL error code = -502
> >Declared cursor already exists
> >
> >STATEMENT:
> >TIB_Query: "<TApplication>.frmSQL.frmQuery.qrQuery."
> >
> >And SqL message:
> >
> >SQL ERROR CODE:-502
> >
> >SQL ERROR MESSAGE:
> >The cursor identified in an OPEN statement is already open.
> >
> >
> >
> >The same SQL was acceptable when I using the other tools such as
> >ibadmin. I was quite confused for what mistake I might take.
>
> I think you were mistake, unless previously you were using an old
beta of
> Firebird or an IB version. Your SQL syntax is wrong and the error
you see
> above came from the database, not from IBO, i.e. it has nothing to
do with IBO.
>
> The reason for the dual cursor error is that your statement attempts to
> "double-dip" on a single cursor by using the wrong syntax for a
re-entrant
> query. Here is the correct SQL:
>
> select a.F1, a.F2, a.Q1,
> (select sum(b.Q1) from MyTable b where b.F1 = a.F1
> and b.F2 <= a.F2) as Q2
> from MyTable a
> order by a.F1, a.F2
>
> By the way, I think you are playing with fire here by having a
primary key
> in your table whose individual elements are used (effectively) in
> calculations. This requirement shouts out for an atomic PK, a
surrogate PK
> populated by a generator.
>
>
> regards,
> Helen Borrie (TeamIBO Support)
>
> ** Please don't email your support questions privately **
> Ask on the list and everyone benefits
> Don't forget the IB Objects online FAQ - link from any page at
> www.ibobjects.com