FreeTDS Development Group

["David Nsengiyumva" <davidn AT finsolutions.co.za>]

Hi Everybody,

Does anyone know how FreeTDS knows the lenght of the returned data; not the
size of the result set, but the individual data in each field of every
particular row in the result set????

For what I see, in the ct-lib layer, the " ct_describe " function sets the
members of the CS_DATAFMT parameter (datafmt) using the TDSCOLINFO (curcol)
structure ("column_size" field of the structure). But what I don't
understand is that when I run a Query that's supposed to return strings
whose lenght is more than 45 it works but when the fields of the returned
values include Date/Time data then it fails.

Basically what happens is that in the " cs_convert " function (ct.c file)
the swicth statement where it checks for " desttype " (switch (desttype)),
it goes to SYBTEXT case and since " len " is greater than " destlen " then
it throws an exception....

I've debugged it and found that "len" is the returned value of the  "
tds_convert " function which also just returns whatever is returned by
different " tds_convert_????? " functions (tds_convert_datetime,
tds_convert_binary, tds_convert_real, etc). In my case it's "
tds_convert_datetime " function and the returned value is 22.

And "destlen" is just the "maxlength" field of the "CS_DATAFMT" structure
that is obtained from the TDSCOLINFO structure. In my case it has value 8. I
really don't anderstand where it gets that value!!!

Anyway I obtain the len > destlen so the " cs_convert " (cs.c file) throws a
"Data-conversion resulted in overflow" exception...

Can you assist please....

David Nsengiyumva

Software Developer
Tel:  +27 21 464 7215
Cel:  +27 73 351 3975
http://www.finsolutions.co.za

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