数据库MySQL（课下作业）

作业要求

1. 下载附件中的world.sql.zip, 参考http://www.cnblogs.com/rocedu/p/6371315.html#SECDB，导入world.sql,提交导入成功截图
2. 编写程序，查询世界上超过“你学号前边七位并把最后一位家到最高位，最高位为0时置1”（比如学号20165201，超过3016520；学号20165208，超过1016520）的所有城市列表，提交运行结果截图
3. 编写程序，查询世界上的所有中东国家的总人口
4. 编写程序，查询世界上的平均寿命最长和最短的国家

具体步骤

1.下载world.sql.zip解压在localhost导入world.sql。

2.查询世界上超过5017530(我的学号为20175303，前七位为2017530，把最后一位3加到最前面，为5017530)的所有城市列表

代码为：

import java.sql.*;
/**
 *InquiryCityList
 *
 * @author 20175303cxd
 * @date 2019/5/4
 */
public class InquiryCityList {
    public static void main(String[] args) throws SQLException {
        Connection con;
        Statement sql;
        ResultSet rs;
        String url = "jdbc:mysql://localhost:3306/world";
        String user = "root";
        String passwd = "";
        con = DriverManager.getConnection(url, user, passwd);
        if (con == null) {
            return;
        }
        String sqlStr = "select*from city where population>5017530";
        try {
            sql = con.createStatement();
            rs = sql.executeQuery(sqlStr);
            while (rs.next()) {
                int id = rs.getInt(1);
                String name = rs.getString(2);
                String countryCode = rs.getString(3);
                String district = rs.getString(4);
                int population = rs.getInt(5);
                System.out.printf("%d	", id);
                System.out.printf("%s	", name);
                System.out.printf("%s	", countryCode);
                System.out.printf("%s	", district);
                System.out.printf("%d
", population);
            }
            con.close();
        } catch (SQLException e) {
            System.out.println("Error:" + e);
        }
    }
}

3.查询世界上的所有中东国家的总人口

代码为：

import java.sql.*;
/**
 *InquiryTotalPopulation
 *
 * @author 20175303cxd
 * @date 2019/5/5
 */
public class InquiryTotalPopulation {
    public static void main(String[] args) throws SQLException {
        Connection con;
        Statement sql;
        ResultSet rs;
        String url = "jdbc:mysql://localhost:3306/world";
        String user = "root";
        String passwd = "";
        con = DriverManager.getConnection(url, user,passwd);
        if (con == null) {
            return;
        }
        String sqlStr = "select Name,Population from country where Region = 'Middle East'";
        try {
            sql = con.createStatement();
            rs = sql.executeQuery(sqlStr);
            int total = 0;
            while (rs.next()) {
                String name = rs.getString(1);
                int population = rs.getInt(2);
                System.out.printf("%s的人口为%d
", name, population);
                total += population;
            }
            System.out.println("中东国家的总人口为：" + total);
        } catch (SQLException e) {
            System.out.println("Error:" + e);
        }
    }
}

4.查询世界上的平均寿命最长和最短的国家

代码为：

import java.sql.*;
/**
 * InquiryCountry
 *
 * @author 20175303cxd
 * @date 2019/5/5
 */
public class InquiryCountry {
    public static void main(String[] args) throws SQLException {
        Connection con;
        Statement sql;
        ResultSet rs;
        String url = "jdbc:mysql://localhost:3306/world";
        String user = "root";
        String passwd = "";
        con = DriverManager.getConnection(url, user,passwd);
        if (con == null) {
            return;
        }
        String sqlStr = "select Name,LifeExpectancy from country order by LifeExpectancy";
        try {
            sql = con.createStatement();
            rs = sql.executeQuery(sqlStr);
            while (rs.next()) {
                float life = rs.getInt(2);
                String name = rs.getString(1);
                rs.first();
                while (life == 0) {
                    rs.next();
                    life = rs.getInt(2);
                }
                name = rs.getString(1);
                System.out.println("世界上平均寿命最短的国家为：" + name);
                rs.last();
                name = rs.getString(1);
                System.out.println("世界上平均寿命最长的国家为：" + name);

            }
        } catch (SQLException e) {
            System.out.println("Error:" + e);
        }
    }
}

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