java连接mysql 使用简单实例

//String jdbcurl="jdbc:mysql://localhost:3306/kang?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC"; 
//String driver = "com.mysql.cj.jdbc.Driver"; 
String jdbcurl="jdbc:mysql://localhost:3306/kang"; 
String driver = "com.mysql.jdbc.Driver"; 
String user = "root"; 
String password = "password"; 
 
​​​​​​​Connection conn = null; 
Statement stmt = null; 
//加载驱动 
Class.forName(driver); 
//连接数据库 
conn = DriverManager.getConnection(jdbcurl,user,password); 
//实例化Statement 对象 
stmt = conn.createStatement(); 
String sql; 
//开启事务 
conn.setAutoCommit(false); 
 
sql = "update student set sname = '王菊2' where sid = 8"; 
conn.prepareStatement(sql).executeUpdate(); 
 
sql = "update student set sname = '郑竹2' where sid = 7"; 
conn.prepareStatement(sql).executeUpdate(); 
 
//提交事务，需要开启事务才行，提交才会执行。 
conn.commit(); 
//事务回滚。一般放在异常处理catch中，需要回滚，否则会跟随下次提交执行。 
conn.rollback(); 
//在finally中需要关闭资源 
rs.close(); 
stmt.close(); 
conn.close(); 
//查询 
sql = "SELECT * FROM student"; 
ResultSet rs = stmt.executeQuery(sql); 
 
SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
 
// 展开结果集数据库 
while(rs.next()){ 
    // 通过字段检索 
    int sid  = rs.getInt("sid"); 
    String sname = rs.getString("sname"); 
    Date sage = rs.getDate("sage"); 
    String ssex = rs.getString("ssex"); 
 
    // 输出数据 
    System.out.print("ID: " + sid); 
    System.out.print(",学生名: " + sname); 
    System.out.print(",生日: " + ft.format(sage)); 
    System.out.println(", 性别 " + ssex); 
}