Alternative iteration over a QList<QTreeWidgetItem*>

[Axtroz]

Greetings.
I have a MySQL table with the following structure:

id | name | parent_node

id | name | parent_node

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`id` is int primary key, auto increment enabled.
`name` is a text string
`parent_node` is an int and holds the id of the previous node.

I query the database and populate a QList<QTreeWidgetItem*> item_list;

while (query->next())
{
   QTreeWidgetItem* tree = new QTreeWidgetItem;
   tree->setText(0, query->value(1).toString());
   tree->setText(1, query->value(0).toString());
   tree->setText(2, query->value(2).toString());
   item_list.append(tree);
}

while (query->next())
{
   QTreeWidgetItem* tree = new QTreeWidgetItem;
   tree->setText(0, query->value(1).toString());
   tree->setText(1, query->value(0).toString());
   tree->setText(2, query->value(2).toString());
   item_list.append(tree);
}

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All is well, but I wonder if my iteration over the list and constructing the tree is optimal. The table contains 10 rows, but in the future it's gonna hold at least 1000 rows and I wonder if the program is going to behave nice, since the tree is constructed on startup (in the main class' constructor).

Here's my iterations:

for (int j=0;j<item_list.count();j++)
        {
          QTreeWidgetItem* current = item_list[j];
        for (int i=0; i<item_list.count();i++)
          {
            qDebug() << "Current item: " << current->text(0);
            if (current->text(2).toInt() == item_list.at(i)->text(1).toInt())
              {
                item_list.at(i)->addChild(current);
              }
            else if (current->text(2).toInt()==0)
              {
                ui->treeWidget->addTopLevelItem(item_list.first());
              }
          }
        }
    }

for (int j=0;j<item_list.count();j++)
        {
          QTreeWidgetItem* current = item_list[j];
        for (int i=0; i<item_list.count();i++)
          {
            qDebug() << "Current item: " << current->text(0);
            if (current->text(2).toInt() == item_list.at(i)->text(1).toInt())
              {
                item_list.at(i)->addChild(current);
              }
            else if (current->text(2).toInt()==0)
              {
                ui->treeWidget->addTopLevelItem(item_list.first());
              }
          }
        }
    }

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Thanks for your help!