Re: How to properly perform this?

Dave,

This is from the gdb session:

Hi, David,

On Sat, Mar 7, 2026 at 1:06 PM Igor Korot <ikorot01(at)gmail(dot)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(at)postgres(dot)rocks> wrote:
> >
> >
> > Dave Cramer
> > www.postgres.rocks
> >
> >
> > On Sat, 7 Mar 2026 at 01:10, Igor Korot <ikorot01(at)gmail(dot)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