In the code below, what do the 1 in GROUP BY and 2 in ORDER BY mean?

SELECT Neighbourhood, AVG(price)
FROM table
GROUP BY 1
ORDER BY 2 DESC;

		Numbers are not valid at that position, and this code would result in a syntax error.
		They are telling SQL to group 1st and sort 2nd.
		1 and 2 are column names in the source table.
		They are referencing the column numbers, i.e. GROUP BY 1 = GROUP BY Neighbourhood, and ORDER BY 2 = ORDER BY AVG(Price)