1.加载驱动(mysql的驱动是com.mysql.jdbc.Driver,SqlServer的驱动是 com.microsoft.sqlserver.jdbc.SQLServerDriver)
2.加载数据库的连接(url, username,password)
3.编写sql语句(String sql="select * from grade where gradeName = ?";)
4.遍历查询结果 【while (resultSet.next()) {
System.out.println(resultSet.getInt("gradeId") + " " + resultSet.getString("gradeName"));
}】
5.关闭资源(从后向前关闭资源 )
public class Test { public static void main(String[] args) { Connection connection = null; PreparedStatement preparedStatement = null; ResultSet resultSet = null; try { // 加载数据库驱动 Class.forName("com.mysql.jdbc.Driver"); // 通过驱动管理类获取数据库链接 connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/myschool?characterEncoding=utf-8", "root", "root"); // 定义sql语句 ?表示占位符 String sql = "select * from grade where gradeName = ?"; // 获取预处理statement preparedStatement = connection.prepareStatement(sql); // 设置参数,第一个参数为sql语句中参数的序号(从1开始),第二个参数为设置的参数值 preparedStatement.setString(1, "二年级"); // 向数据库发出sql执行查询,查询出结果集 resultSet = preparedStatement.executeQuery(); // 遍历查询结果集 while (resultSet.next()) { System.out.println(resultSet.getInt("gradeId") + " " + resultSet.getString("gradeName")); } } catch (Exception e) { e.printStackTrace(); } finally { // 释放资源 if (resultSet != null) { try { resultSet.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (preparedStatement != null) { try { preparedStatement.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (connection != null) { try { connection.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } }
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