dal manuale di mysql
Columns selected for output can be referred to in ORDER BY and GROUP BY clauses using column names, column aliases, or column positions. Column positions are integers and begin with 1:
mysql> SELECT college, region, seed FROM tournament
-> ORDER BY region, seed;
mysql> SELECT college, region AS r, seed AS s FROM tournament
-> ORDER BY r, s;
mysql> SELECT college, region, seed FROM tournament
-> ORDER BY 2, 3;
To sort in reverse order, add the DESC (descending) keyword to the name of the column in the ORDER BY clause that you are sorting by. The default is ascending order; this can be specified explicitly using the ASC keyword. Use of column positions is deprecated because the syntax has been removed from the SQL standard.
Quindi dovrebbe essere SELECT * FROM tabella ORDER BY campo DESC