編寫程序,查詢世界上的平均壽命最長和最短的國家html
package MySQL; import java.sql.*; public class getCity { public static void main(String[] args) { Connection con; Statement sql; ResultSet rs; con = GetDBConnection.connectDB("world","root",""); 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>1017520) { 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); } } }
package MySQL; import java.sql.*; public class getPopulation { 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("中東國家的總人口爲"+totalpopulation); con.close(); } catch (SQLException e) { System.out.println(e); } } }
package MySQL; import java.sql.*; public class getlife { 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("世界上平均壽命最短的國家爲:"+lowcountry+" 壽命爲"+number1); rs.last(); float number2 = rs.getInt(8); highcountry = rs.getString(2); System.out.println("世界上平均壽命最長的國家爲:"+highcountry+" 壽命爲"+number2); con.close(); } catch (SQLException e) { System.out.println(e); } } }
package MySQL; 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");//加載JDBC-MySQL驅動 } catch(Exception e){} try{ con = DriverManager.getConnection(uri,id,p); //鏈接代碼 } catch(SQLException e){} return con; } }
碼雲連接(https://gitee.com/cjy-123/20175218cjy/tree/master/week10/mysql)java