mysql> select count(year='2006' or null) as '2006' ,count(year='2009' or null) as '2008' from y;
+------+------+
| 2006 | 2008 |
+------+------+
| 2 | 1 |
+------+------+
1 row in set (0.00 sec)
查看是否开启慢查询日志 show variables like 'slow_query_log'
设置没有索引的记录到慢查询日志 set global log_queries_not_using_indexes=on
查看超过多长时间的sql进行记录到慢查询日志 show variables like 'long_query_time'
设置慢查询的时间 set long_query_time=1
