数据库MySQL(课下作业，必做)

一、任务详情

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
1. 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
1. 编写程序，查询世界上的所有中东国家的总人口
1. 编写程序，查询世界上的平均寿命最长和最短的国家

二、源代码

1.任务二源代码：

import java.sql.*;
public class SelectCity {
    public static void main(String args[]) {
        Connection con;
        Statement sql;
        ResultSet rs;
        con = GetDBConnection.connectDB("world","root","");
        if(con == null ) {
            return;
        }
        String c3=" population >7017521";
        String sqlStr =
                "select * from city where "+c3;
        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(e);
        }
    }
}

2.任务三源代码：

import java.sql.*;
public class SumPopulation {
    public static void main(String args[]) {
        Connection con;
        Statement sql;
        ResultSet rs;
        con = GetDBConnection.connectDB("world","root","");
        if(con == null ) {
            return;
        }
        String c3=" Region='Middle East'";
        String sqlStr =
                "select * from country where "+c3;
        try {
            int sum=0;
            sql=con.createStatement();
            rs = sql.executeQuery(sqlStr);
            while(rs.next()) {
                int p=rs.getInt(5);
                sum+=p;
            }
            System.out.println("世界上所有中东国家的总人口数为："+sum);
            con.close();
        }
        catch(SQLException e) {
            System.out.println(e);
        }
    }
}

3.任务四源代码

import java.sql.*;
public class getLifeExpectancy {
    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);
            String name1,name2;
            rs.first();
            float f=rs.getFloat(8);
            while (f==0.0){
                rs.next();
                f=rs.getFloat(8);
            }
            name1=rs.getString(2);
            System.out.println("世界上的平均寿命最短的国家是："+name1);
            rs.last();
            name2=rs.getString(2);
            System.out.println("世界上的平均寿命最长的国家是："+name2);
            con.close();
        }
        catch(SQLException e) {
            System.out.println(e);
        }
    }
}