create_ctas_nodata(List *tlist, IntoClause *into)
{
	List	   *attrList;
	ListCell   *t,
			   *lc;

	/*
	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
	 * column name list was specified in CREATE TABLE AS, override the column
	 * names in the query.  (Too few column names are OK, too many are not.)
	 */
	attrList = NIL;
	lc = list_head(into->colNames);
	foreach(t, tlist)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(t);

		if (!tle->resjunk)
		{
			ColumnDef  *col;
			char	   *colname;

			if (lc)
			{
				colname = strVal(lfirst(lc));
				lc = lnext(into->colNames, lc);
			}
			else
				colname = tle->resname;

			col = makeColumnDef(colname,
								exprType((Node *) tle->expr),
								exprTypmod((Node *) tle->expr),
								exprCollation((Node *) tle->expr));

			/*
			 * It's possible that the column is of a collatable type but the
			 * collation could not be resolved, so double-check.  (We must
			 * check this here because DefineRelation would adopt the type's
			 * default collation rather than complaining.)
			 */
			if (!OidIsValid(col->collOid) &&
				type_is_collatable(col->typeName->typeOid))
				ereport(ERROR,
						(errcode(ERRCODE_INDETERMINATE_COLLATION),
						 errmsg("no collation was derived for column \"%s\" with collatable type %s",
								col->colname,
								format_type_be(col->typeName->typeOid)),
						 errhint("Use the COLLATE clause to set the collation explicitly.")));

			attrList = lappend(attrList, col);
		}
	}

	if (lc != NULL)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("too many column names were specified")));

	/* Create the relation definition using the ColumnDef list */
	return create_ctas_internal(attrList, into);
}
create_ctas_nodata(List *tlist, IntoClause *into)
{
	List	   *attrList;
	ListCell   *t,
			   *lc;

	 
	attrList = NIL;
	lc = list_head(into->colNames);
	foreach(t, tlist)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(t);

		if (!tle->resjunk)
		{
			ColumnDef  *col;
			char	   *colname;

			if (lc)
			{
				colname = strVal(lfirst(lc));
				lc = lnext(into->colNames, lc);
			}
			else
				colname = tle->resname;

			col = makeColumnDef(colname,
								exprType((Node *) tle->expr),
								exprTypmod((Node *) tle->expr),
								exprCollation((Node *) tle->expr));

			 
			if (!OidIsValid(col->collOid) &&
				type_is_collatable(col->typeName->typeOid))
				ereport(ERROR,
						(errcode(ERRCODE_INDETERMINATE_COLLATION),
						 errmsg("no collation was derived for column \"%s\" with collatable type %s",
								col->colname,
								format_type_be(col->typeName->typeOid)),
						 errhint("Use the COLLATE clause to set the collation explicitly.")));

			attrList = lappend(attrList, col);
		}
	}

	if (lc != NULL)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("too many column names were specified")));

	 
	return create_ctas_internal(attrList, into);
}