线下作业MySQL #20175201

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
相关问题

GetDBConnection类由于系统版本不同，经过网上搜索改为

• task1
• @author Fomalhaut20175201
• @date 2019/5/4
  /
  import java.sql.;
  public class GetDBConnection {
  public static Connection connectDB(String DBName,String id,String p) {
  Connection con = null;
  String
  uri = "jdbc:mysql://localhost:3306/"+DBName+"?serverTimezone=GMT%2B8&characterEncoding=utf-8";
  try{ Class.forName("com.mysql.cj.jdbc.Driver");//加载JDBC-MySQL驱动
  }
  catch(Exception e){}
  try{
  con = DriverManager.getConnection(uri,id,p); //连接代码
  }
  catch(SQLException e){}
  return con;
  }
  }

相关步骤
一、world.sql

1.下载相关附件并解压。
2.在数据库单击右键，运行sql文件，选择sql文件，点击开始。
3.导入完成后，重新打开连接会有显示。
二、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”

1.学号为20175214 查询为超过3017520
2.实验代码

• task1
• @author Fomalhaut20175201
• @date 2019/5/4
  */

import java.sql.*;
public class task1 {
public static void main(String[] args) {
Connection con;
Statement sql;
ResultSet rs;
con = GetDBConnection.connectDB("world","root","123");
if(con == null) {
return;
}
try {
sql=con.createStatement();
rs = sql.executeQuery("SELECT * FROM city");
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);
if(Population>6017520) {
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(e);
}
}
}

3.相关截图

三、编写程序，查询世界上的所有中东国家的总人口

1.相关代码

• task2
• @author 20175201
• @date 2019/5/4
  */

import java.sql.*;
public class task2 {
public static void main(String[] args) {
Connection con;
Statement sql;
ResultSet rs;
con = GetDBConnection.connectDB("world","root","123");
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);
}
}
}

2.截图
四、编写程序，查询世界上的平均寿命最长和最短的国家

1.相关代码

• task2
• @author 20175201
• @date 2019/5/4
  /
  import java.sql.;
  public class task3 {
  public static void main(String[] args) {
  Connection con;
  Statement sql;
  ResultSet rs;
  con = GetDBConnection.connectDB("world","root","123");
  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);
  }
  }
  }

2.截图