说明：  用JAVA连接数据库主要有两种方式，一是用JDBC-ODBC桥来连接，二是用相关厂商提供的相应驱动程序来连接，首先谈谈第一种连接。
(JAVA connect with the database are mainly in two ways, one using JDBC-ODBC bridge to connect, and the other is providing manufacturers with the relevant corresponding driver to connect to, let us talk about the first connection.)