Function mysql_new_select

sql/sql_parse.cc:7551–7635

*/

bool
mysql_new_select(LEX *lex, bool move_down, SELECT_LEX *select_lex)
{
  THD *thd= lex->thd;
  bool new_select= select_lex == NULL;
  int old_nest_level= lex->current_select->nest_level;
  DBUG_ENTER("mysql_new_select");

  if (new_select)
  {
    if (!(select_lex= new (thd->mem_root) SELECT_LEX()))
      DBUG_RETURN(1);
    select_lex->select_number= ++thd->lex->stmt_lex->current_select_number;
    select_lex->parent_lex= lex; /* Used in init_query. */
    select_lex->init_query();
    select_lex->init_select();
  }
  select_lex->nest_level_base= &thd->lex->unit;
  if (move_down)
  {
    lex->nest_level++;
    if (select_lex->set_nest_level(old_nest_level + 1))
      DBUG_RETURN(1);
    SELECT_LEX_UNIT *unit;
    /* first select_lex of subselect or derived table */
    if (!(unit= lex->alloc_unit()))
      DBUG_RETURN(1);

    unit->include_down(lex->current_select);
    unit->return_to= lex->current_select;
    select_lex->include_down(unit);
    /*
      By default we assume that it is usual subselect and we have outer name
      resolution context, if no we will assign it to 0 later
    */
    select_lex->context.outer_context= &select_lex->outer_select()->context;
  }
  else
  {
    bool const outer_most= (lex->current_select->master_unit() == &lex->unit);
    if (outer_most && lex->result)
    {
      my_error(ER_WRONG_USAGE, MYF(0), "UNION", "INTO");
      DBUG_RETURN(TRUE);
    }

    /*
      This type of query is not possible in the grammar:
        SELECT 1 FROM t1 PROCEDURE ANALYSE() UNION ... ;

      But this type of query is still possible:
        (SELECT 1 FROM t1 PROCEDURE ANALYSE()) UNION ... ;
      and it's not easy to disallow this grammatically,
      because there can be any parenthesis nest level:
        (((SELECT 1 FROM t1 PROCEDURE ANALYSE()))) UNION ... ;
    */
    if (lex->proc_list.elements!=0)
    {