mysql> set profiling=1;mysql> select distinct(num) from test_test;mysql> select num from test_test group by num;mysql> show profiles;
+----------+------------+-------------------------------------
06 | Query_ID| Duration | Query |
08 | 1 | 0.00072550 | select distinct(num) from test_test
09 | 2 | 0.00071650 | select num from test_test group by num
