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【第17章：Java数据库编程】_ResultSet接口

发布时间：2021-01-10 11:11:26编辑：雪饮阅读（）

 数据库的查询操作

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
public class TestJava{
       public static final String DBDRIVER="org.gjt.mm.mysql.Driver";
       public static final String DBURL="jdbc:mysql://localhost:3306/xy";
       public static final String DBUSER="root";
       public static final String DBPASS="";
       public static void main(String args[]) throws Exception{  
              Class.forName(DBDRIVER);
              Connection conn=DriverManager.getConnection(DBURL,DBUSER,DBPASS);
              String sql="select id,title,content,created_at,user_name from message";
              Statement stmt=conn.createStatement();
              ResultSet rs=stmt.executeQuery(sql);
              while(rs.next()){
                    
                     int id=rs.getInt("id");
                     String user_name=rs.getString("user_name");
                     String content=rs.getString("content");
                     String title=rs.getString("title");
                     java.util.Date created_at=rs.getDate("created_at");
                    
                     System.out.print("id:"+id+" ");
                     System.out.print("content:"+content+" ");
                     System.out.print("title:"+title+" ");
                     System.out.print("created_at:"+created_at+" ");
                     System.out.println();
              }
              stmt.close();
              rs.close();
              conn.close();
       }
}

在查询到数据后取出遍历每条数据并获取该条数据的某个字段时，若觉得每次都要输出字段名有点麻烦，特别是当某个字段名很长时候，就更觉得麻烦，那么其实也可以根据查询sql中select所选中的这几个字段的顺序编号来取对应字段，如：
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
public class TestJava{
       public static final String DBDRIVER="org.gjt.mm.mysql.Driver";
       public static final String DBURL="jdbc:mysql://localhost:3306/xy";
       public static final String DBUSER="root";
       public static final String DBPASS="";
       public static void main(String args[]) throws Exception{  
              Class.forName(DBDRIVER);
              Connection conn=DriverManager.getConnection(DBURL,DBUSER,DBPASS);
              String sql="select id,title,content,created_at,user_name from message";
              Statement stmt=conn.createStatement();
              ResultSet rs=stmt.executeQuery(sql);
              while(rs.next()){
                    
                     int id=rs.getInt(1);
                     String user_name=rs.getString(5);
                     String content=rs.getString(3);
                     String title=rs.getString(2);
                     java.util.Date created_at=rs.getDate(4);
                    
                     System.out.print("id:"+id+" ");
                     System.out.print("content:"+content+" ");
                     System.out.print("title:"+title+" ");
                     System.out.print("created_at:"+created_at+" ");
                     System.out.println();
              }
              stmt.close();
              rs.close();
              conn.close();
       }
}
D:\>javac TestJava.java
D:\>java TestJava
id:3 content:How are you? title:hello kasumi created_at:2021-01-10
id:4 content:snowDink, are you ok recently? I am kasumi title:hello snowDrink created_at:2021-01-10