原始表student字段：
mysql> select column_name,data_type
-> from information_schema.columns
-> where table_name = 'student';
+-------------+-----------+
| column_name | data_type |
+-------------+-----------+
| stu_id| int|
| stu_name| varchar|
| stu_tel| int|
| stu_score| int|
+-------------+-----------+
4 rows in set (0.01 sec)
表中原始数据：
mysql> select * from student;
+--------+----------+---------+-----------+
| stu_id | stu_name | stu_tel | stu_score |
+--------+----------+---------+-----------+
|1 | a|151 |60 |
|2 | b|152 |61 |
|3 | c|153 |62 |
|4 | d|154 |63 |
+--------+----------+---------+-----------+
4 rows in set (0.00 sec)
索引创建格式：
create [ <index type> ] index <index name> [ using {btree | hash} ] on table specification ( <column in index> [,<column in index> ] )
<index type> := unique | fulltext | spatial
<column in index>:=<column name> [asc | desc]
创建一个最简单的索引：
mysql> create index stu_index
-> on student(stu_id);
Query OK, 0 rows affected (0.36 sec)
Records: 0Duplicates: 0Warnings: 0
这里创建立一个非唯一性的索引，其中默认使用asc升序排列。
如果没有指定using声明的话，mysql自动创建一个B树。所以上面的索引其实是这样子的：
mysql> create index stu_index using btree
-> on student(stu_id asc);
Query OK, 0 rows affected (0.19 sec)
Records: 0Duplicates: 0Warnings: 0
当然，btree索引可以换成哈希索引。
也可以为多个列创建唯一的索引：
mysql> create unique index stu_index using hash
-> on student(stu_id,stu_name);
Query OK, 0 rows affected (0.19 sec)
Records: 0Duplicates: 0Warnings: 0
添加索引：
mysql> alter table student
-> add unique index stu_index2
-> using hash (stu_tel);
Query OK, 0 rows affected (0.36 sec)
Records: 0Duplicates: 0Warnings: 0
删除索引：
mysql> drop index stu_index on student;
Query OK, 0 rows affected (0.22 sec)
Records: 0Duplicates: 0Warnings: 0
创建表时定义索引：
mysql> create table student(
-> stu_idint primary key,
-> stu_namevarchar(5) not null,
-> stu_telint(5) unique,
-> stu_scoreint(2),
-> index stu_index(stu_id)
-> );
只需在表的最后添加创建索引的语句即可。
视图是数据库中的虚拟表，它存储的不是自己的内容，而是经过select从其他表整合而来的。当其他表的内容改变是，视图内的内容跟着改变。在一定条件下，对视图的更新也将改变源表。
创建视图：
create [ or replace ] view <view name> [<column list>] as <table expression> [with [ cascaded |local ] check option ]
mysql> create view view1 as
-> (select * from student);
Query OK, 0 rows affected (0.16 sec)
mysql> select * from view1;
+--------+----------+---------+-----------+
| stu_id | stu_name | stu_tel | stu_score |
+--------+----------+---------+-----------+
|1 | a|151 |60 |
|2 | b|152 |61 |
|3 | c|153 |62 |
|4 | d|154 |63 |
+--------+----------+---------+-----------+
4 rows in set (0.00 sec)
创建视图时，如果视图已存在，可用replace重新覆盖创建。
创建视图时还可以更改原始列名。
mysql> create or replace view view1(id,name,tel,score) as
-> (select * from student);
Query OK, 0 rows affected (0.03 sec)
mysql> select * from view1;
+----+------+------+-------+
| id | name | tel| score |
+----+------+------+-------+
|1 | a|151 |60 |
|2 | b|152 |61 |
|3 | c|153 |62 |
|4 | d|154 |63 |
+----+------+------+-------+
4 rows in set (0.00 sec)
当一个视图可以更新时，就能够使用[with [ cascaded |local ] check option ]选项对更新对有效检查。
删除视图：
drop view view1;
