FreeTDS Development Group

[Brian Bruns <camber AT ais.org>]

Eric,

I've checked in some changes to CVS to fix this, if you want to try it out
and let me know.  The basic problem is that binding with CS_NULL_TERM
returns a length that includes the null, so the length of 'test' would be
5.  Most of the convert functions returned the correct amount (5) but a
few including numeric and float returned the size sans null (4 in the
example).

Since CS_FMT_NULLTERM was implemented before CS_UNUSED, it was
historically CS_FMT_UNUSED that decremented the value.  Instead I've
switched things around so CS_FMT_NULLTERM increments the value.

This should also fix flt8, and money as well.

Brian

On Fri, 9 Mar 2001, Eric Deutsch wrote:

> 
> Regarding the problem of NUMERIC values getting truncated, about
> which I posted a few days ago:
> 
> After hunting around in the FreeTDS code for a good bit, I think
> I have located the source of my problem, although I don't
> understand why.  I'm hoping someone can help clarify.
> 
> To recap, I created a table like this:
> 
> CREATE TABLE dbo.dbaccesstests (
>       test_id         int identity,
>       intfield        int,
>       charfield       varchar(50),
>       numfield        numeric(10,0),
>       floatfield      float,
>       datefield       datetime
>       )
> 
> I inserted a few rows, and then SELECTed them back out:
> 
> 1 | 20 | butter | 12 | 3.1415 | Jan 25 2000 06:00P
> 2 | 25 | milk | 456 | 2.17 | Jan 22 2001 12:00A
> 3 | 30 | swamp gas | 8901 | 1.23456789012346 | May 10 1998 10:11P
> 4 | 35 | pillow | 123456789 | 1.23456789012346 | Mar 09 2001 09:38A
> 
> I noticed that in the numeric columns, the last digit was always
> missing.  Later, I noticed that the same was true for the datetime
> strings (the "M" is missing from AM and PM).
> 
> I've found the piece of code that it apparently responsible for
> this:
> 
> ct.c: (line ~490)
>             case CS_FMT_UNUSED:
>                if (desttype==SYBCHAR) {
>                   len--;
>                }
>                break;      
> 
> If I add a line:  len++; reversing the subtraction here, then the
> resulting query returns the correct results:
> 
> 1 | 20 | butter | 123 | 3.1415 | Jan 25 2000 06:00PM
> 2 | 25 | milk | 4567 | 2.17 | Jan 22 2001 12:00AM
> 3 | 30 | swamp gas | 89012 | 1.23456789012346 | May 10 1998 10:11PM
> 4 | 35 | pillow | 1234567890 | 1.23456789012346 | Mar 09 2001 09:40AM
> 
> This appears to solve my problem, but I worry that this breaks
> something else.  It seems that for the varchar(50) column, the len
> variable is indeed one larger than necessary, and this len-- is
> beneficial in that reduces len to the correct value.  However,
> since the string has a trailing NULL, this larger len doesn't
> seem to matter, anyway.
> 
> Does anyone know what the original purpose of that len-- was, or
> otherwise understand the implications of this issue better??
> 
> Maybe the right thing to do is make a change like the following:
> 
>             case CS_FMT_UNUSED:
>                if (desttype==SYBCHAR
>               && (srctype==SYBCHAR || srctype==SYBVARCHAR)) {
>                   len--;
>                }
> /*            fprintf(stderr,"** debug: dest='%s', len=%d\n",dest,len); */
>                break;      
> 
> This appears to work correctly for all the cases I've tried.
> 
> Comments? Does this problem affect anyone else?
> 
> thanks,
> Eric
> 
>