视图是一个虚拟表（非真实存在），其本质是【根据SQL语句获取动态的数据集，并为其命名】，用户使用时只需使用【名称】即可获取结果集，并可以将其当作表来使用
create view viewname as select tname from table1,table2 where condition
MariaDB [test2]> create view student2 as select * from student; Query OK, 0 rows affected (0.02 sec) MariaDB [test2]> show tables; +-----------------+ | Tables_in_test2 | +-----------------+ | a | | b | | student | | student2 | +-----------------+ 4 rows in set (0.00 sec)
drop view viewname
MariaDB [test2]> drop view student2; Query OK, 0 rows affected (0.00 sec) MariaDB [test2]> show tables; +-----------------+ | Tables_in_test2 | +-----------------+ | a | | b | | student | +-----------------+ 3 rows in set (0.00 sec)
alter view viewname as select tname from table1,table2 where condition
MariaDB [test2]> alter view student2 as select * from a; Query OK, 0 rows affected (0.00 sec)
原文：http://www.cnblogs.com/lixiang1013/p/7294040.html