1
create table t1 (a int primary key);
2
insert into t1 values (1),(2),(3);
3
explain select * from t1 order by a desc;
4
id select_type table type possible_keys key key_len ref rows Extra
5
1 SIMPLE t1 index NULL PRIMARY 4 NULL 3 Using index
6
select * from t1 order by a desc;