表 test2
mysql> desc test2;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| a1 | varchar(20) | YES | MUL | NULL | |
| a2 | varchar(20) | YES | | NULL | |
| a3 | varchar(20) | YES | | NULL | |
| a4 | varchar(20) | YES | | NULL | |
| a5 | varchar(20) | YES | | NULL | |
| a6 | varchar(20) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+创建索引:mysql> create index inx_a on test2(a1);
Query OK, 3 rows affected (0.02 sec)
Records: 3 Duplicates: 0 Warnings: 0没有问题我在创建非聚集索引时用如下命令:
create nonclustered index id_a on test2(a2);报错:mysql> create nonclustered index id_a on test2(a2);
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'nonclustered index id_a on test2(a2)' at line 1
哪点写错了呀??谢谢回答!
mysql> desc test2;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| a1 | varchar(20) | YES | MUL | NULL | |
| a2 | varchar(20) | YES | | NULL | |
| a3 | varchar(20) | YES | | NULL | |
| a4 | varchar(20) | YES | | NULL | |
| a5 | varchar(20) | YES | | NULL | |
| a6 | varchar(20) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+创建索引:mysql> create index inx_a on test2(a1);
Query OK, 3 rows affected (0.02 sec)
Records: 3 Duplicates: 0 Warnings: 0没有问题我在创建非聚集索引时用如下命令:
create nonclustered index id_a on test2(a2);报错:mysql> create nonclustered index id_a on test2(a2);
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'nonclustered index id_a on test2(a2)' at line 1
哪点写错了呀??谢谢回答!
INNODB,主键就是 聚集索引,你也无法修改
mysql索引分类:http://longxzq-126-com.javaeye.com/blog/591273