1. select * from test  where a=xx group by b order by c   如何加索引

CREATE TABLE `index_test` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(100) NOT NULL DEFAULT '',
`gid` int(11) NOT NULL DEFAULT '0',
`age` int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

MysqL> select * from index_test;
+----+------------+-----+
| id | name | gid |
+----+------------+-----+
| 1 | taoshihan | 2 |
| 2 | taoshihan1 | 2 |
+----+------------+-----+

2. 加个联合索引试试

alter table index_test add index name_gid_age_index(name,gid,age);

explain select * from index_test where name='taoshihan' group by gid order by age;