JDBC 复习笔记1

public class JDBC {

public static void main(String[] args) {

Connection cn = null;
Statement sm = null;
ResultSet rs = null;
String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "decamincow";

try {

//mysql对于接口实现的驱动进行加载
Class.forName("com.mysql.jdbc.Driver");

cn = DriverManager.getConnection(url, user, password);

//设置事务提交
cn.setAutoCommit(false);

//设置事务隔离级别
//ct.setTransactionIsolation(level);

//sm用于向数据库发送要执行的SQL语句
sm = cn.createStatement();

//创建学生表
sm.executeUpdate
("CREATE TABLE student("
+ "id int(10) NOT NULL AUTO_INCREMENT,   "
+ "name varchar(20),  "
+ "password varchar(20),  "
+ "PRIMARY KEY (id)  )");

//插入一个学生信息
sm.executeUpdate
("INSERT INTO student(name, password) VALUES('xiaoming','123');");

//错误代码
//			int err = 1/0;

//插入一个学生信息
sm.executeUpdate
("INSERT INTO student(name, password) VALUES('xiaohong','123');");

//事务提交
cn.commit();

//查询，如果把错误注掉便能查到刚插入的数据
rs = sm.executeQuery("SELECT * FROM student");

//根据数据库显示行返回，如果到最后的空行返回false
while(rs.next()){

//根据列取
System.out.println("name " + rs.getString(2) + "password" + rs.getString(3));

//根据列名取
System.out.println("name " + rs.getString("name") + "password" + rs.getString("password"));

}

} catch (Exception e) {
e.printStackTrace();
try {

//事务回滚，这样xiaoming和xiaohong都不会出现
//MD我发现建表的操作在mysql中不回滚，但是我觉的可以在这里执行删表操作
cn.rollback();
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}finally{

//关闭资源
if (sm != null){
try {
sm.close();
} catch (SQLException e) {
e.printStackTrace();
}
sm = null;
}
if (cn != null){
try {
cn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
cn = null;
}
}

}

}