package itheima;

import java.sql.*;

public class JdbcTest {
public static void main(String[] args) {
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;

    try {
        // 載入資料庫驅動
        Class.forName("com.mysql.cj.jdbc.Driver");

        // 通過驅動管理類獲取資料庫連結
        connection = DriverManager.getConnection
                ("jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true", "root", "root");
        // 定義sql語句 ?表示佔位符
        String sql = "select * from user where username = ?";
        // 獲取預處理statement
        preparedStatement = connection.prepareStatement(sql);
        // 設定引數，第一個引數為sql語句中引數的序號（從1開始），第二個引數為設定的引數值
        preparedStatement.setString(1, "王五");
        // 向資料庫發出sql執行查詢，查詢出結果集
        resultSet = preparedStatement.executeQuery();
        // 遍歷查詢結果集
        while (resultSet.next()) {
            System.out.println(resultSet.getString("id") + "  " + resultSet.getString("username"));
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        // 釋放資源
        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();
            }
        }
    }
}
 

}