数据库MySQL(课下作业，必做)

任务一

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

任务二

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

任务三

3. 编写程序，查询世界上的所有中东国家的总人口

任务四

4. 编写程序，查询世界上的平均寿命最长和最短的国家

运行截图

任务一

任务二

任务三

任务四

代码

import java.sql.*;

public class MySQL1 {
    public static void main(String[] args) {
        Connection con;
        Statement sql;
        ResultSet rs;
        con = GetDBConnection.connectDB("world", "root", "");
        if (con == null) {
            return;
        }
        String sqlStr = "select*from city where population>7015533";
        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\t", id);
                System.out.printf("%s\t", name);
                System.out.printf("%s\t", countryCode);
                System.out.printf("%s\t", district);
                System.out.printf("%d\n", population);
            }
            con.close();
        } catch (SQLException e) {
            System.out.println("Error:" + e);
        }


    }
}

import java.sql.*;
public class MySQL2 {
    public static void main(String[] args) {
        Connection con;
        Statement sql;
        ResultSet rs;
        con = GetDBConnection.connectDB("world","root","");
        if(con == null) {
            return;
        }
        String sqlStr = "select * from country where Region = 'Middle East'";
        try {
            sql = con.createStatement();
            rs = sql.executeQuery(sqlStr);
            long totalpopulation = 0;
            while(rs.next()) {
                int Population = rs.getInt(7);
                totalpopulation +=Population;
            }
            System.out.println("中东国家的总人口为"+totalpopulation);
            con.close();
        }
        catch (SQLException e) {
            System.out.println(e);
        }
    }
}

import java.sql.*;
public class MySQL3 {
    public static void main(String[] args) {
        Connection con;
        Statement sql;
        ResultSet rs;
        con = GetDBConnection.connectDB("world","root","");
        if(con == null) {
            return;
        }
        String sqlStr = "select * from country order by LifeExpectancy";
        try {
            sql = con.createStatement();
            rs = sql.executeQuery(sqlStr);
            rs.first();
            String highcountry,lowcountry;
            float number1 = rs.getInt(8);
            while(number1 == 0) {
                rs.next();
                number1 = rs.getInt(8);
            }
            lowcountry = rs.getString(2);
            System.out.println("世界上平均寿命最短的国家为："+lowcountry+" 寿命为"+number1);
            rs.last();
            float number2 = rs.getInt(8);
            highcountry = rs.getString(2);
            System.out.println("世界上平均寿命最长的国家为："+highcountry+" 寿命为"+number2);
            con.close();
        }
        catch (SQLException e) {
            System.out.println(e);
        }
    }
}

代码链接

https://gitee.com/yukungbhy/yukun-20155335/commit/5b68564f0df846a941ab9db74bc2e431b1db8460