bool Item_ref::fix_fields(THD *thd, Item **reference)
{
  enum_parsing_place place= NO_MATTER;
  DBUG_ASSERT(fixed == 0);
  SELECT_LEX *current_sel= thd->lex->current_select;

  if (set_properties_only)
  {
    /* do nothing */
  }
  else if (!ref || ref == not_found_item)
  {
    DBUG_ASSERT(reference_trough_name != 0);
    if (!(ref= resolve_ref_in_select_and_group(thd, this,
                                               context->select_lex)))
      goto error;             /* Some error occurred (e.g. ambiguous names). */

    if (ref == not_found_item) /* This reference was not resolved. */
    {
      Name_resolution_context *last_checked_context= context;
      Name_resolution_context *outer_context= context->outer_context;
      Field *from_field;
      ref= 0;

      if (!outer_context)
      {
        /* The current reference cannot be resolved in this query. */
        my_error(ER_BAD_FIELD_ERROR,MYF(0),
                 this->full_name(), thd->where);
        goto error;
      }

      /*
        If there is an outer context (select), and it is not a derived table
        (which do not support the use of outer fields for now), try to
        resolve this reference in the outer select(s).

        We treat each subselect as a separate namespace, so that different
        subselects may contain columns with the same names. The subselects are
        searched starting from the innermost.
      */
      from_field= (Field*) not_found_field;

      do
      {
        SELECT_LEX *select= outer_context->select_lex;
        Item_subselect *prev_subselect_item=
          last_checked_context->select_lex->master_unit()->item;
        last_checked_context= outer_context;

        /* Search in the SELECT and GROUP lists of the outer select. */
        if (outer_context->resolve_in_select_list)
        {
          if (!(ref= resolve_ref_in_select_and_group(thd, this, select)))
            goto error; /* Some error occurred (e.g. ambiguous names). */
          if (ref != not_found_item)
          {
            DBUG_ASSERT(*ref && (*ref)->fixed);
            prev_subselect_item->used_tables_and_const_cache_join(*ref);
            break;
          }
          /*
            Set ref to 0 to ensure that we get an error in case we replaced
            this item with another item and still use this item in some
            other place of the parse tree.
          */
          ref= 0;
        }

        place= prev_subselect_item->parsing_place;
        /*
          Check table fields only if the subquery is used somewhere out of
          HAVING or the outer SELECT does not use grouping (i.e. tables are
          accessible).
          TODO:
          Here we could first find the field anyway, and then test this
          condition, so that we can give a better error message -
          ER_WRONG_FIELD_WITH_GROUP, instead of the less informative
          ER_BAD_FIELD_ERROR which we produce now.
        */
        if ((place != IN_HAVING ||
             (!select->with_sum_func &&
              select->group_list.elements == 0)))
        {
          /*
            In case of view, find_field_in_tables() write pointer to view
            field expression to 'reference', i.e. it substitute that
            expression instead of this Item_ref
          */
          from_field= find_field_in_tables(thd, this,
                                           outer_context->
                                             first_name_resolution_table,
                                           outer_context->
                                             last_name_resolution_table,
                                           reference,
                                           IGNORE_EXCEPT_NON_UNIQUE,
                                           TRUE, TRUE);
          if (! from_field)
            goto error;
          if (from_field == view_ref_found)
          {
            Item::Type refer_type= (*reference)->type();
            prev_subselect_item->used_tables_and_const_cache_join(*reference);
            DBUG_ASSERT((*reference)->type() == REF_ITEM);
            mark_as_dependent(thd, last_checked_context->select_lex,
                              context->select_lex, this,
                              ((refer_type == REF_ITEM ||
                                refer_type == FIELD_ITEM) ?
                               (Item_ident*) (*reference) :
                               0), false);
            /*
              view reference found, we substituted it instead of this
              Item, so can quit
            */
            return FALSE;
          }
          if (from_field != not_found_field)
          {
            if (cached_table && cached_table->select_lex &&
                outer_context->select_lex &&
                cached_table->select_lex != outer_context->select_lex)
            {
              /*
                Due to cache, find_field_in_tables() can return field which
                doesn't belong to provided outer_context. In this case we have
                to find proper field context in order to fix field correctly.
              */
              do
              {
                outer_context= outer_context->outer_context;
                select= outer_context->select_lex;
                prev_subselect_item=
                  last_checked_context->select_lex->master_unit()->item;
                last_checked_context= outer_context;
              } while (outer_context && outer_context->select_lex &&
                       cached_table->select_lex != outer_context->select_lex);
            }
            prev_subselect_item->used_tables_cache|= from_field->table->map;
            prev_subselect_item->const_item_cache= 0;
            break;
          }
        }
        DBUG_ASSERT(from_field == not_found_field);

        /* Reference is not found => depend on outer (or just error). */
        prev_subselect_item->used_tables_cache|= OUTER_REF_TABLE_BIT;
        prev_subselect_item->const_item_cache= 0;

        outer_context= outer_context->outer_context;
      } while (outer_context);

      DBUG_ASSERT(from_field != 0 && from_field != view_ref_found);
      if (from_field != not_found_field)
      {
        Item_field* fld;
        if (!(fld= new (thd->mem_root) Item_field(thd, from_field)))
          goto error;
        thd->change_item_tree(reference, fld);
        mark_as_dependent(thd, last_checked_context->select_lex,
                          current_sel, fld, fld, false);
        /*
          A reference is resolved to a nest level that's outer or the same as
          the nest level of the enclosing set function : adjust the value of
          max_arg_level for the function if it's needed.
        */
        if (thd->lex->in_sum_func &&
            thd->lex == context->select_lex->parent_lex &&
            thd->lex->in_sum_func->nest_level >= 
            last_checked_context->select_lex->nest_level)
          set_if_bigger(thd->lex->in_sum_func->max_arg_level,
                        last_checked_context->select_lex->nest_level);
        return FALSE;
      }
      if (ref == 0)
      {
        /* The item was not a table field and not a reference */
        my_error(ER_BAD_FIELD_ERROR, MYF(0),
                 this->full_name(), thd->where);
        goto error;
      }
      /* Should be checked in resolve_ref_in_select_and_group(). */
      DBUG_ASSERT(*ref && (*ref)->fixed);
      mark_as_dependent(thd, last_checked_context->select_lex,
                        context->select_lex, this, this, false);
      /*
        A reference is resolved to a nest level that's outer or the same as
        the nest level of the enclosing set function : adjust the value of
        max_arg_level for the function if it's needed.
      */
      if (thd->lex->in_sum_func &&
          thd->lex == context->select_lex->parent_lex &&
          thd->lex->in_sum_func->nest_level >= 
          last_checked_context->select_lex->nest_level)
        set_if_bigger(thd->lex->in_sum_func->max_arg_level,
                      last_checked_context->select_lex->nest_level);
    }
  }

  DBUG_ASSERT(*ref);
  /*
    Check if this is an incorrect reference in a group function or forward
    reference. Do not issue an error if this is:
      1. outer reference (will be fixed later by the fix_inner_refs function);
      2. an unnamed reference inside an aggregate function.
  */
  if (!((*ref)->type() == REF_ITEM &&
       ((Item_ref *)(*ref))->ref_type() == OUTER_REF) &&
      (((*ref)->with_sum_func && name &&
        !(current_sel->linkage != GLOBAL_OPTIONS_TYPE &&
          current_sel->having_fix_field)) ||
       !(*ref)->fixed))
  {
    my_error(ER_ILLEGAL_REFERENCE, MYF(0),
             name, ((*ref)->with_sum_func?
                    "reference to group function":
                    "forward reference in item list"));
    goto error;
  }

  set_properties();

  if ((*ref)->check_cols(1))
    goto error;
  return FALSE;

error:
  context->process_error(thd);
  return TRUE;
}
bool Item_ref::fix_fields(THD *thd, Item **reference)
{
  enum_parsing_place place= NO_MATTER;
  DBUG_ASSERT(fixed == 0);
  SELECT_LEX *current_sel= thd->lex->current_select;

  if (set_properties_only)
  {
     
  }
  else if (!ref || ref == not_found_item)
  {
    DBUG_ASSERT(reference_trough_name != 0);
    if (!(ref= resolve_ref_in_select_and_group(thd, this,
                                               context->select_lex)))
      goto error;              

    if (ref == not_found_item)  
    {
      Name_resolution_context *last_checked_context= context;
      Name_resolution_context *outer_context= context->outer_context;
      Field *from_field;
      ref= 0;

      if (!outer_context)
      {
         
        my_error(ER_BAD_FIELD_ERROR,MYF(0),
                 this->full_name(), thd->where);
        goto error;
      }

       
      from_field= (Field*) not_found_field;

      do
      {
        SELECT_LEX *select= outer_context->select_lex;
        Item_subselect *prev_subselect_item=
          last_checked_context->select_lex->master_unit()->item;
        last_checked_context= outer_context;

         
        if (outer_context->resolve_in_select_list)
        {
          if (!(ref= resolve_ref_in_select_and_group(thd, this, select)))
            goto error;  
          if (ref != not_found_item)
          {
            DBUG_ASSERT(*ref && (*ref)->fixed);
            prev_subselect_item->used_tables_and_const_cache_join(*ref);
            break;
          }
           
          ref= 0;
        }

        place= prev_subselect_item->parsing_place;
         
        if ((place != IN_HAVING ||
             (!select->with_sum_func &&
              select->group_list.elements == 0)))
        {
           
          from_field= find_field_in_tables(thd, this,
                                           outer_context->
                                             first_name_resolution_table,
                                           outer_context->
                                             last_name_resolution_table,
                                           reference,
                                           IGNORE_EXCEPT_NON_UNIQUE,
                                           TRUE, TRUE);
          if (! from_field)
            goto error;
          if (from_field == view_ref_found)
          {
            Item::Type refer_type= (*reference)->type();
            prev_subselect_item->used_tables_and_const_cache_join(*reference);
            DBUG_ASSERT((*reference)->type() == REF_ITEM);
            mark_as_dependent(thd, last_checked_context->select_lex,
                              context->select_lex, this,
                              ((refer_type == REF_ITEM ||
                                refer_type == FIELD_ITEM) ?
                               (Item_ident*) (*reference) :
                               0), false);
             
            return FALSE;
          }
          if (from_field != not_found_field)
          {
            if (cached_table && cached_table->select_lex &&
                outer_context->select_lex &&
                cached_table->select_lex != outer_context->select_lex)
            {
               
              do
              {
                outer_context= outer_context->outer_context;
                select= outer_context->select_lex;
                prev_subselect_item=
                  last_checked_context->select_lex->master_unit()->item;
                last_checked_context= outer_context;
              } while (outer_context && outer_context->select_lex &&
                       cached_table->select_lex != outer_context->select_lex);
            }
            prev_subselect_item->used_tables_cache|= from_field->table->map;
            prev_subselect_item->const_item_cache= 0;
            break;
          }
        }
        DBUG_ASSERT(from_field == not_found_field);

         
        prev_subselect_item->used_tables_cache|= OUTER_REF_TABLE_BIT;
        prev_subselect_item->const_item_cache= 0;

        outer_context= outer_context->outer_context;
      } while (outer_context);

      DBUG_ASSERT(from_field != 0 && from_field != view_ref_found);
      if (from_field != not_found_field)
      {
        Item_field* fld;
        if (!(fld= new (thd->mem_root) Item_field(thd, from_field)))
          goto error;
        thd->change_item_tree(reference, fld);
        mark_as_dependent(thd, last_checked_context->select_lex,
                          current_sel, fld, fld, false);
         
        if (thd->lex->in_sum_func &&
            thd->lex == context->select_lex->parent_lex &&
            thd->lex->in_sum_func->nest_level >= 
            last_checked_context->select_lex->nest_level)
          set_if_bigger(thd->lex->in_sum_func->max_arg_level,
                        last_checked_context->select_lex->nest_level);
        return FALSE;
      }
      if (ref == 0)
      {
         
        my_error(ER_BAD_FIELD_ERROR, MYF(0),
                 this->full_name(), thd->where);
        goto error;
      }
       
      DBUG_ASSERT(*ref && (*ref)->fixed);
      mark_as_dependent(thd, last_checked_context->select_lex,
                        context->select_lex, this, this, false);
       
      if (thd->lex->in_sum_func &&
          thd->lex == context->select_lex->parent_lex &&
          thd->lex->in_sum_func->nest_level >= 
          last_checked_context->select_lex->nest_level)
        set_if_bigger(thd->lex->in_sum_func->max_arg_level,
                      last_checked_context->select_lex->nest_level);
    }
  }

  DBUG_ASSERT(*ref);
   
  if (!((*ref)->type() == REF_ITEM &&
       ((Item_ref *)(*ref))->ref_type() == OUTER_REF) &&
      (((*ref)->with_sum_func && name &&
        !(current_sel->linkage != GLOBAL_OPTIONS_TYPE &&
          current_sel->having_fix_field)) ||
       !(*ref)->fixed))
  {
    my_error(ER_ILLEGAL_REFERENCE, MYF(0),
             name, ((*ref)->with_sum_func?
                    "reference to group function":
                    "forward reference in item list"));
    goto error;
  }

  set_properties();

  if ((*ref)->check_cols(1))
    goto error;
  return FALSE;

error:
  context->process_error(thd);
  return TRUE;
}