FreeTDS Development Group

[Norbert Matzke <matzke AT geopp.de>]

ZIGLIO, Frediano, VF-IT wrote:
> > ZIGLIO, Frediano, VF-IT wrote:
> > > > Problem: My client ODBC application needs to bind 
> > parameters which are
> > > > UTF-8 encoded to SQL insert/update statements.
> > > > I have set ClientCharset to UTF-8 in freetds.conf.
> > > >
> > > > I did some tests with Version 0.82 of FreeTDS and SQL Server 2005.
> > > > Seemed to work, but not with a short UTF-8 String like '€'.
> > > > '€' is 3 bytes long in UTF-8 encoding.
> > > >
> > > > If I called
> > > > SQLBindParameter( , ,SQL_C_CHAR, SQL_WVARCHAR, n, 0, , , &ind )
> > > > with n=1 and *ind=3 I got an error message. iconv was not able to
> > > > convert '€' and SQL Server complains also ...
> > > >
> > > > Calling with n=3 and *ind=3 succeeds but inserts the 
> > string '€  ' into
> > > > the database because the Server pads with 2 blanks to the 
> > > > requested size
> > > > of 3 CHARS.
> > > >
> > > > Setting *ind=SQL_NTS did not help.
> > > >
> > > > I have tested version 0.83dev 2008-10-09 also: It did not work at
> > > > all using UTF-8 strings with non single byte UTF-8 characters.
> > > >
> > > > So I have had a look at what is going on inside the FreeTDS code
> > > > (ver. 0.83dev) and found that the problem arises due to 
> > insufficient
> > > > buffer space for the bounded parameter.
> > > >
> > > > I solved the problem with very small changes to tds/mem.c and
> > > > odbc/sql2tds.c (see attached patch). For me it works now.
> > > >
> > > > Any comments on this issue ?
> > > >
> > > > Best regards,
> > > > Norbert
> > > It's strange that every time you implement a feature 
> > someone ask for another... well, this means that previous 
> > works as expected I hope :)
> > > WVARCHAR is currently in progress. I don't think is 
> > supported by 0.82 and have some problems (there is a failing 
> > test) under CVS HEAD. Test related to your problem should be 
> > utf8, I'll test with your string.
> > > Actually I'm quite busy so I have no timeline for this issue.
> > >
> > > freddy77
> > I was not aware of the fact that utf-8 support is quite new 
> > to FreeTDS.
> > I have had a look at the documentation before I tried to use it, a few
> > days ago, and it seemed to me that by setting the Client Charset to
> > UTF-8 one can use a MS SQL Server like any other UTF-8 capable DMBS --
> > though MS SQL Server itself is not UTF-8 capable ! This is a very
> > valuable feature of FreeTDS !
> >
> > Besides, if I understand correctly, requesting SQL_WVARCHAR vs. 
> > SQL_VARCHAR as SQL parameter type does not make any diffence 
> > to FreeTDS 
> > ? Only the server will not_do/do a USC-2 --> CP1252 --> UCS-2
> > conversion with the data ? (assuming CREATE TABLE ... NVARCHAR() ..)
> >
> > Norbert
>
> Well... SQL_WVARCHAR have problems. FreeTDS support UTF-8 as client encoding 
> converting as best as it can but using SQL_VARCHAR. There is a big difference 
> between SQL_VARCHAR and SQL_WVARCHAR cause FreeTDS should use VARCHAR or 
> NVARCHAR on server. Currently not supporting SQL_WVARCHAR means that you have 
> to use SQL_VARCHAR which lead to VARCHAR so you can't represent much 
> characters. When FreeTDS will support SQL_WVARCHAR any UCS-2 characters will 
> be available to your client.
>
> freddy77

That sounds strange to me. I just did another test and found the
following behaviour:

- SQLBindParameter(... SQL_C_CHAR, SQL_WVARCHAR, 7, ..., "utf-8 €", ,&9)
  Sending Packet ==> ...  P1 NCHAR(7) ...

- SQLBindParameter(... SQL_C_CHAR, SQL_VARCHAR, 7, ..., "utf-8 €", ,&9)
  Sending Packet ==> ...  P1 CHAR(7) ...

In both cases the iconv is called freetds internal (for the wire
conversion) to UC2-2 with source encoding UTF-8 (due to Client Charset
setting). Data on the wire is the same !
So it should depend only on the server (and the CREATE TABLE column
type) which kind of storage conversion is applied.

Norbert