Function reinit_stmt_before_use

sql/sql_prepare.cc:3063–3220

*/

void reinit_stmt_before_use(THD *thd, LEX *lex)
{
  SELECT_LEX *sl= lex->all_selects_list;
  DBUG_ENTER("reinit_stmt_before_use");
  Window_spec *win_spec;

  /*
    We have to update "thd" pointer in LEX, all its units and in LEX::result,
    since statements which belong to trigger body are associated with TABLE
    object and because of this can be used in different threads.
  */
  lex->thd= thd;
  DBUG_ASSERT(!lex->explain);

  if (lex->empty_field_list_on_rset)
  {
    lex->empty_field_list_on_rset= 0;
    lex->field_list.empty();
  }
  for (; sl; sl= sl->next_select_in_list())
  {
    if (sl->changed_elements & TOUCHED_SEL_COND)
    {
      /* remove option which was put by mysql_explain_union() */
      sl->options&= ~SELECT_DESCRIBE;

      /* see unique_table() */
      sl->exclude_from_table_unique_test= FALSE;

      /*
        Copy WHERE, HAVING clause pointers to avoid damaging them
        by optimisation
      */
      if (sl->prep_where)
      {
        /*
          We need this rollback because memory allocated in
          copy_andor_structure() will be freed
        */
        thd->change_item_tree((Item**)&sl->where,
                              sl->prep_where->copy_andor_structure(thd));
        sl->where->cleanup();
      }
      else
        sl->where= NULL;
      if (sl->prep_having)
      {
        /*
          We need this rollback because memory allocated in
          copy_andor_structure() will be freed
        */
        thd->change_item_tree((Item**)&sl->having,
                              sl->prep_having->copy_andor_structure(thd));
        sl->having->cleanup();
      }
      else
        sl->having= NULL;
      DBUG_ASSERT(sl->join == 0);