Re: How to properly perform this? - Mailing list pgsql-odbc

Dave,

This is from the gdb session:

Hi, David,

On Sat, Mar 7, 2026 at 1:06 PM Igor Korot <ikorot01@gmail.com> wrote:
>
> Hi, Dave,
> I think its just an empty column.
>
> Is there a way to treat it as NULL?
>
> P.S.: Sorry for top-posting.
>
> On Sat, Mar 7, 2026 at 5:41 AM Dave Cramer <davecramer@postgres.rocks> wrote:
> >
> >
> > Dave Cramer
> > www.postgres.rocks
> >
> >
> > On Sat, 7 Mar 2026 at 01:10, Igor Korot <ikorot01@gmail.com> wrote:
> >>
> >> Hi, ALL,
> >> I'm trying to execute following query:
> >>
> >> draft=# SELECT c.relname AS name, ixs.tablespace, ARRAY(SELECT
> >> a.attname FROM pg_attribute a WHERE a.attrelid = idx.indrelid AND
> >> a.attnum = ANY(idx.indkey) AND a.attnum > 0 ORDER BY
> >> array_position(idx.indkey, a.attnum) OFFSET idx.indnkeyatts) AS
> >> included, c.reloptions AS storage FROM pg_index idx, pg_class c,
> >> pg_namespace n, pg_class t, pg_indexes ixs WHERE ixs.indexname =
> >> c.relname AND c.oid = idx.indexrelid AND t.oid = idx.indrelid AND
> >> n.oid = c.relnamespace AND idx.indisprimary AND n.nspname = 'public'
> >> AND t.relname = 'leagues';
> >>      name     | tablespace | included | storage
> >> --------------+------------+----------+---------
> >>  leagues_pkey |            | {}       |
> >> (1 row)
> >>
> >>
> >> My code is as follows:
> >>
> >>             while( ( ret = SQLGetData( m_hstmt, 4, SQL_C_WCHAR,
> >> index_param.get(), 255, &ind[3] ) ) != SQL_NO_DATA )
> >>             {
> >>                 if( ret == SQL_SUCCESS || ret == SQL_SUCCESS_WITH_INFO )
> >>                 {
> >>                     auto numBytes = ind[3];
> >>                     if( ind[3] == SQL_NO_TOTAL )
> >>                         numBytes = 255;
> >>                     else if( ind[3] > 255 )
> >>                         numBytes = 255;
> >>                     str_to_uc_cpy( options, index_param.get() );
> >>                 }
> >>                 else
> >>                 {
> >>                     GetErrorMessage( errorMsg, STMT_ERROR  );
> >>                     result = 1;
> >>                 }
> >>             }
> >> Unfortunately it goes into the loop because apparently the driver or
> >> the server keeps seeing the last column as having data and returns
> >> SQL_SUCCESS.
> >>
> >> What is the proper way to resolve this?
> >>
> >> I'm using unixODBC with PostgreSQL 16.
> >>
> >> My odbc.ini looks like this:
> >>
> >> [code]
> >> [postgres]
> >> Driver=Postgres
> >> Description=Postgres ODBC Driver
> >> UserId=postgres
> >> Password=XXX
> >> Servername=localhost
> >> Database=draft
> >> Port=5432
> >>
> >> [/code]
> >>
> >>
> >> What is the best way to proceed?
> >
> >
> > is the last column empty or null?
> >
> > if not null then there is data there.

 3754                while( ( ret = SQLGetData( m_hstmt, 3,
SQL_C_WCHAR, included.get(), 255, &ind[2] ) ) != SQL_NO_DATA )
(gdb) n
3756                    if( ret == SQL_SUCCESS || ret == SQL_SUCCESS_WITH_INFO )
(gdb) p ind[2]
$1 = 4
(gdb) n
3758                        auto numBytes = ind[2];
(gdb)
3759                        if( ind[2] == SQL_NO_TOTAL )
(gdb)
3761                        else if( ind[2] > 255 )
(gdb)
3763                        str_to_uc_cpy( includedCol, included.get() );
(gdb)
3764                    }
(gdb)
3754                while( ( ret = SQLGetData( m_hstmt, 3,
SQL_C_WCHAR, included.get(), 255, &ind[2] ) ) != SQL_NO_DATA )
(gdb)
3771                includedCol.erase( 0, 1 );
(gdb) p ind[2]
$2 = 4
(gdb) p ret
$3 = 100
(gdb) n

This is what happens with column 3 when the array is empty.

3779            while( ( ret = SQLGetData( m_hstmt, pos, SQL_C_WCHAR,
index_param.get(), 255, &ind[3] ) ) != SQL_NO_DATA )
(gdb)
3781                if( ret == SQL_SUCCESS || ret == SQL_SUCCESS_WITH_INFO )
(gdb) p ind[3]
$4 = -1
(gdb) p ret
$5 = 0
(gdb) n
3783                    auto numBytes = ind[3];
(gdb)
3784                    if( ind[3] == SQL_NO_TOTAL )
(gdb)
3786                    else if( ind[3] > 255 )
(gdb)
3788                    str_to_uc_cpy( options, index_param.get() );
(gdb)
3789                }
(gdb)
3779            while( ( ret = SQLGetData( m_hstmt, pos, SQL_C_WCHAR,
index_param.get(), 255, &ind[3] ) ) != SQL_NO_DATA )
(gdb)
3781                if( ret == SQL_SUCCESS || ret == SQL_SUCCESS_WITH_INFO )
(gdb) p ind[3]
$6 = -1
(gdb) p ret
$7 = 0
(gdb)

And this one is for column 4 of the query.

The column is NULL, so no data is there.

I think it's a bug in the driver as it should return SQL_NO_DATA on
the very first call....

Thank you.

> >
> > Dave