FreeTDS Development Group

["Thompson, Bill D (London)" <ThompBil AT exchange.uk.ml.com>]

OK all,

I've gotten (eventually) to the bottom of this!

It all stems, as I thought, from my rework of ctlibrary, although not from
the CS_EXPOSE_FMTS issue ...

it turns out that if you have an empty result set ( select * from table
where 1 = 2 ), that ct_results() should return with a result type of
CS_ROW_RESULT, even though there isn't one!
I tested this with sqsh 1.7 (and some printfs) linked to the sybase
libraries.

Looking back at the old code, I notice a flag in the command structure (
called empty_res_hack ) , whose purpose was not clear to me, and which I had
thought I could do away with.
Alas, I was wrong. 

I have worked a patch for this, which should wing its way to you , early
next week. 
needless to say my version of the flag is no longer so unfortunately named,
although, to paraphrase Shakespeare:
"A hack by any other name would smell as sweet...NOT!"

Bill 

> -----Original Message-----
> From: Thompson, Bill D (London) 
> Sent: 04 February 2003 09:56
> To:   'freetds AT lists.ibiblio.org'
> Subject:      RE: [freetds] Possible bug: DBD::Sybase + current FreeTDS +
> selectall_hashref
> 
> Hi,
> 
> I suspect this problem is down to my re-working of the "results
> processing" some while back.
> I had to rework both the tds_process_results() functions and also the
> ct_results() function.
> 
> In this, I took advice from the Sybase ct-library manual, in which it
> states (in the ct_results routine description):
> 
> "An application will not receive format results unless the Client-Library
> CS_EXPOSE_FMTS property is set to CS_TRUE."
> I impmemented this, and the code in ct_config() to enable this property to
> be toggled.
> I assumed the default setting of this property to be CS_FALSE, although
> looking over the manuals again, I cant find anything that supports this
> assumption (or, to be fair, it's converse). Also, It looks like I didn't
> add the code to ct_con_props(), which also allows this property to be
> toggled. One or two things need to be done:
> 1) set the default for this property to be CS_TRUE, instead of CS_FALSE
> 2) implement the code in ct_con_props() to allow this property to be
> toggled. It may be the case that a call to this function is being
> "ignored" in the ct_con_props() function.
> 
> HTH
> Bill 
> 
> 
> 
>       -----Original Message-----
>       From:   Michael Peppler [SMTP:mpeppler AT peppler.org]
>       Sent:   04 February 2003 01:08
>       To:     freetds AT lists.ibiblio.org
>       Subject:        Re: [freetds] Possible bug: DBD::Sybase + current
> FreeTDS + selectall_hashref
> 
>       On Mon, 2003-02-03 at 11:19, Martin Schroth wrote:
>       > Hi,
>       > 
>       > DBI gets the following error if there are no rows to return:
>       > Can't get DBI::st=HASH(0x...)->{NAME}: unrecognised attribute
>       > 
>       > Example:
>       > my $stmt = "SELECT 1 FROM test WHERE 1=0"
>       > my $hash = $dbh->selectall_hashref($stmt,1);
> 
>       This works fine when used with the Sybase libs, so I suspect a
> slight
>       difference in return values.
> 
> 
> 
>       >     -> execute for DBD::Sybase::st
> (DBI::st=HASH(0x81f9964)~0x81f9940)
>       > thr#804b3c0
>       >     syb_st_execute() -> ct_command() OK
>       >     syb_st_execute() -> ct_send() OK
>       >     st_next_result() -> ct_results(4046) == 1
> 
>       And this is the difference. With the Sybase libs I get:
> 
>           syb_st_execute() -> ct_command() OK
>           syb_st_execute() -> ct_send() OK
>           st_next_result() -> ct_results(4040) == 1
>           ct_res_info() returns 1 columns
>           ct_describe(0): type = 8, maxlen = 4
>           describe() -> col 0, type 8, realtype 8
>       describe() retcode = 1
>           st_next_result() -> lasterr = 0, lastsev = 0
> 
>       FreeTDS returns no data at all, whereas you should still get the
> column
>       description even if there are no rows returned.
> 
>       Michael
>       -- 
>       Michael Peppler                              Data Migrations, Inc.
>       mpeppler AT peppler.org                 http://www.mbay.net/~mpeppler
>       Sybase T-SQL/OpenClient/OpenServer/C/Perl developer available for
> short or 
>       long term contract positions -
> http://www.mbay.net/~mpeppler/resume.html
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