MySQL 视图

同时要操作数据库中两个表的信息，用javabean存储，用视图关联两个表，然后用javabean把视图中的字段封装起来，就可以取到了。
MERGE
with check option

mysql> CREATE TABLE t (qty INT, price INT);

mysql> INSERT INTO t VALUES(3, 50);

mysql> CREATE VIEW v AS SELECT qty, price, qty*price AS value FROM t;

mysql> SELECT * FROM v;

+------+-------+-------+

| qty  | price | value |

+------+-------+-------+

|    3 |    50 |   150 |

+------+-------+-------+