createSubqueryForCorresponding.c

 /*
 * Returns a subquery selecting outputColumns from main_arg.
 * main_arg is modified and returned.
 */
static SelectStmt *
createSubqueryForCorresponding(List* outputColumns, SelectStmt* main_arg)
{
	ColumnRef *cr;
	ResTarget *rt;
	SelectStmt *n;

	RangeSubselect * rss;
	ListCell* mctl;

	n = makeNode(SelectStmt);
	n->targetList = NIL;
	foreach(mctl, outputColumns)
	{
		TargetEntry *mctle = (TargetEntry *) lfirst(mctl);

		cr = makeNode(ColumnRef);
		cr->fields = list_make1(makeString(mctle->resname));
		cr->location = -1;

		rt = makeNode(ResTarget);
		rt->name = NULL;
		rt->indirection = NIL;
		rt->val = (Node *)cr;
		rt->location = -1;

		n->targetList = lappend(n->targetList, rt);
	}

	rss = makeNode(RangeSubselect);

	// XXX makeAlias alias name should be empty??
	rss->alias = makeAlias("", NULL);
rss->subquery = (Node *)main_arg;

	n->fromClause = list_make1(rss);

	main_arg = n;

	return main_arg;
}