The SHOW PROFILE and SHOW PROFILES statements display profiling information that indicates resource usage for statements executed during the course of the current session.
1、开启PROFILE（这对会话开启）：
Profiling is controlled by the profiling session variable, which has a default value of 0 (OFF). Profiling is enabled by setting profiling to 1 or ON:
mysql> select  @@profiling;
+-------------+
| @@profiling |
+-------------+
|           0 |
+-------------+
1 row in set (0.00 sec)

mysql> set profiling=1;
Query OK, 0 rows affected (0.00 sec)

2、查看开启情况：

mysql> select @@profiling;
+-------------+
| @@profiling |
+-------------+
|           1 |
+-------------+
1 row in set (0.00 sec)


3、做几次查下，然后用show profiles查看：
mysql> show profiles;
+----------+------------+------------------+
| Query_ID | Duration   | Query            |
+----------+------------+------------------+
|        1 | 0.01432675 | select  * from c |
|        2 | 0.00025350 | select  * from c |
+----------+------------+------------------+
显示的是当前会话的执行的最近的sql语句，查询的默认记录值是15条，最大值是100.

mysql> show profile all for query 2;