example15_6.java.bak

不错的教程 适合中高级人员的使用

import java.sql.*;
import java.util.LinkedList;
public class Example15_6
{  public static void main(String args[])
   {   LinkedList list=new LinkedList();
	   Connection con;Statement sql; ResultSet rs;
      try {  Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  
          }
     catch(ClassNotFoundException e)
          {  System.out.println(""+e);
          }
      try
          { 
             con=DriverManager.getConnection("jdbc:odbc:sun","gxy","123");
             sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
             rs=sql.executeQuery("SELECT name,math FROM chengjibiao");
             rs.last();
			 int lownumber=rs.getRow();
			 int number=lownumber;
			 for(int i=1;i<=number;i++)
			  {
				 list.add(new Integer(i));
			 }
			 double sum=0;
			 int k=4;
			 int 抽取数目=k;
			 while(k>0)
			  {
				 int i=(int)(Math.random()*list.size());
				 int index=((Integer)list.get(i)).intValue();
				 rs.absolute(index);
				 System.out.print("姓名:"+rs.getString(1));
				 System.out.println("数学:"+rs.getString(2));
				 int math=rs.getInt("math");
				 sum=sum+math;
				 k--;
				 list.remove(i);
			   }
			   System.out.println("抽样的数学平均成绩："+sum/抽取数目);
            con.close();
           }
      catch(SQLException e1) {}
   
   }    
}