execute block returns( non_empty_table varchar(31 )) as
declare v_cnt int;
declare v_expr varchar(2048);
begin
    for
    with
    s as(
        select
            r.rdb$relation_name tname
            ,rf.rdb$field_position fpos
            ,rf.rdb$field_name fname
        from rdb$relations r
        join rdb$relation_fields rf on r.rdb$relation_name=rf.rdb$relation_name
        where coalesce(r.rdb$system_flag,0)=0 -- не смотрим на системные таблицы
        and r.rdb$relation_type not in(4,5) -- убираем GTT'шки
        and r.rdb$view_source is null -- убираем вьюхи
    )
    ,c as(
        select
        s.tname,s.fname,s.fpos
        ,'+coalesce(count('||trim(lower(s.fname))||'),0)' cnt
        from s
    )
    select c.tname,'select '||substring(list(c.cnt,'') from 2) ||' from '||lower(c.tname) expr
    from c
    group by c.tname
    into non_empty_table, v_expr
    do begin
        execute statement (v_expr) into v_cnt;
        if (v_cnt=0) then suspend;
    end
end