JDBC 开发基础

package top.simba1949;
import com.mysql.jdbc.Driver;
import org.junit.Test;
import java.sql.*;
/**
 * @author SIMBA1949
 * @date 2019/8/24 17:21
 */
public class ApplicationTest {
    /**
     *
     * @throws SQLException
     */
    @Test
    public void jdbcTest() throws SQLException {
        // 注册驱动
        DriverManager.deregisterDriver(new Driver());
        // 获取连接
        String url = "jdbc:mysql://127.0.0.1:3306/db_sql_learn?serverTimezone=Asia/Shanghai";
        String username = "root";
        String password = "19491001";
        Connection connection = DriverManager.getConnection(url, username, password);
        // 获取可执行的 SQL 语句对象
        Statement statement = connection.createStatement();
        String sql = "select * from student";
        statement.execute(sql);
        // 处理结果
        ResultSet resultSet = statement.getResultSet();
        while (resultSet.next()){
            // getXXX(int column) ：根据每一行数据获取对应列的值，从 1 开始
            System.out.print(resultSet.getObject(1) + " | ");
            System.out.print(resultSet.getObject(2) + " | ");
            System.out.print(resultSet.getObject(3) + " | ");
            System.out.println(resultSet.getObject(4) + " | ");
        }
        // 释放资源
        resultSet.close();
        statement.close();
        connection.close();
    }
    /**
     * 预编译
     * @throws SQLException
     */
    @Test
    public void jdbcPrepareTest() throws SQLException {
        // 注册驱动
        DriverManager.deregisterDriver(new Driver());
        // 获取连接
        String url = "jdbc:mysql://127.0.0.1:3306/db_sql_learn?serverTimezone=Asia/Shanghai";
        String username = "root";
        String password = "19491001";
        Connection connection = DriverManager.getConnection(url, username, password);
        // 获取可执行的 SQL 语句对象, 预编译对象
        String sql = "select * from student where id > ?";
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        // 设置占位符的值
        preparedStatement.setInt(1, 41);
        preparedStatement.executeQuery();
        // 处理结果
        ResultSet resultSet = preparedStatement.getResultSet();
        while (resultSet.next()){
            // getXXX(int column) ：根据每一行数据获取对应列的值，从 1 开始
            System.out.print(resultSet.getObject(1) + " | ");
            System.out.print(resultSet.getObject(2) + " | ");
            System.out.print(resultSet.getObject(3) + " | ");
            System.out.println(resultSet.getObject(4) + " | ");
        }
        // 释放资源
        resultSet.close();
        preparedStatement.close();
        connection.close();
    }
}