Question Re: Utralite crashes using subquery with CASE in Technology Q&A

Utralite crashes using subquery with CASE

Former Member — Mon, 29 Oct 2012 15:39:11 GMT

I have a query that causes a crash in Ultralite, both in the iPad and Interactive SQL. The crash began to happen after I installed EBF 3798. Before that, the query was executed without error.

The original query is somewhat complex, but I succeeded in devising a simple query that causes the crash as well.

The query is:

select * from (
    select 
    A.id as i,
       case A.num 
            when 0 then 'a'
            when 1 then 'b'
            when 2 then 'c'
            else 'd'
       end as v,
       v + ' - ' + A.num as s
    from testTable A
) as X(i, v, s)
where i = 1

And the Ultralite database has only one table:

create table testTable
(
     id int primary key,
     num int,
     descr varchar(100)
)

The crash occurs when executing ULConnection's PrepareStatement method. And the table does not need to have any data in it.

If I remove the enclosing select, the problem does not happen again. Also, if remove either column v (the one that contains the case statement) or column s, that concatenates the preceding field with another field from the table, the problem does not occur any longer.

Those solutions are not acceptable, because the outer query is generated at runtime, in other to add extra filters to an existing query.

Re: Utralite crashes using subquery with CASE

Breck_Carter — Mon, 29 Oct 2012 16:48:58 GMT

That query shouldn't ever work because of the ambiguous use of the "+" operator (is it numeric addition? is it string concatenation?), and it does fail in in SQL Anywhere 12.0.1.3298 Classic (non-UltraLite) as follows:

create table testTable
(
     id int primary key,
     num int,
     descr varchar(100)
);
INSERT testTable VALUES ( 1, 1, 'x' );
COMMIT;
select * from (
    select 
    A.id as i,
       case A.num 
            when 0 then 'a'
            when 1 then 'b'
            when 2 then 'c'
            else 'd'
       end as v,
       v + ' - ' + A.num as s
    from testTable A
) as X(i, v, s)
where i = 1;

There was an error reading the results of the SQL statement.
The displayed results may be incorrect or incomplete.
Cannot convert 'b - ' to a numeric
SQLCODE=-157, ODBC 3 State="07006"

Try using STRING() instead of "+"; this query works:

select * from (
    select 
    A.id as i,
       case A.num 
            when 0 then 'a'
            when 1 then 'b'
            when 2 then 'c'
            else 'd'
       end as v,
       STRING ( v, ' - ', A.num ) as s
    from testTable A
) as X(i, v, s)
where i = 1;

i,v,s
1,'b','b - 1'

Re: Utralite crashes using subquery with CASE

Former Member — Mon, 29 Oct 2012 17:21:12 GMT

I changed the query to use STRING instead of "+", but it still crashes on iPad and in InteractiveSQL for Mac OS.

Also, I changed the query to

select *
from (
select 
   A.id as i,
   (case A.num 
        when 0 then 'a'
        when 1 then 'b'
        when 2 then 'c'
        else 'd'
   end) as v,
   v + ' - ' + A.descr as s
from testTable A
) as X(i, v, s)

where i = 1

The crash always happens, and the first time when there was an ambiguity, Ultralite did not return any error. It simply crashes.

Re: Utralite crashes using subquery with CASE

jeff_albion — Mon, 29 Oct 2012 17:56:57 GMT

I believe this is an instance of CR #717377 fixed in 12.0.1.3803.

Re: Utralite crashes using subquery with CASE

Former Member — Tue, 30 Oct 2012 12:51:16 GMT

I can confirm the crash also happens to me using the above query. I'm also using the 3798 EBF, as far as I know it is the latest Ultralite EBF for iOS, or there is any more recent?

Re: Utralite crashes using subquery with CASE

Former Member — Tue, 30 Oct 2012 17:48:49 GMT

I haven't found this version in the EBF list. Is it available for download? If not, when will it be?

Thanks.

Re: Utralite crashes using subquery with CASE

former_SQLA_member1694876 — Thu, 01 Nov 2012 13:33:46 GMT

Hi Antonio,

Thank you for posting this concise repro. I confirm that the crash was fixed in 12.0.1.3803. There was a further bug that your query exposed, and that is now fixed with 12.0.1.3812. I have requested an EBF be released.

And thank you Breck for correcting the query. Indeed, UL does (now) report -157 (conversion error) for 'b -' -> numeric with the original query.

Re: Utralite crashes using subquery with CASE

Former Member — Tue, 13 Nov 2012 09:24:06 GMT

Hi Tim,

Do you have any news about the EBF?

Re: Utralite crashes using subquery with CASE

jeff_albion — Tue, 13 Nov 2012 15:13:23 GMT

Hello Antonio,

This issue has been reported and fixed underneath CR #723102. The Windows / Mac OS 12.0.1 EBFs have been requested for this issue and are currently being built and tested internally.

If you require an immediate update for when the EBF is released (or a "pre-release" copy for your own testing purposes), we invite you to open a technical support case so that we can discuss this with you directly and properly address your individual business needs.

Re: Utralite crashes using subquery with CASE

former_SQLA_member1694876 — Wed, 12 Dec 2012 13:30:09 GMT

This should be posted now (build 3819), and also includes proper iPhone 5/Xcode 4.5 support.