📄 example5_4.jsp

📁 可以让初学者有一个感性的认识

💻 JSP

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<HTML>
<%@page contentType="text/html;charset=GB2312"%>
<%@page import="java.sql.*" %>

<BODY bgcolor=cyan><Font size=3>

<%	String name,xuehao;
	int math;

	Connection con;
	Statement sql;
	ResultSet rs;
	
	try
	{
		Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
	}catch(ClassNotFoundException e){}
	
	try
	{
		con=DriverManager.getConnection("jdbc:odbc:sun","","");
		sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
		rs=sql.executeQuery("SELECT * FROM students");
		out.print("<Table Border>");
			out.print("<TR>");
				out.print("<TH width=100>"+"学号");
				out.print("<TH width=100>"+"姓名");
				out.print("<TH width=50>" +"数学成绩");
			out.print("</TR>");
			rs.last();
			int lownumber=rs.getRow();
			int number=lownumber;
			double sum=0;
			int 抽取数目=4;
			int old_i[]={0,0,0,0};
			int k=抽取数目;
			int j=0;
			while(抽取数目>0)
			{
				int i=(int)(Math.random()*number+1);
				boolean boo=false;
				for(int m=0;m<old_i.length;m++)
					if(i==old_i[m])boo=true;
				if(boo)continue;
				rs.absolute(i);
				out.print("<TR>");
					xuehao=rs.getString(1);
					out.print("<TD>"+xuehao+"</TD>");
					name=rs.getString(2);
					out.print("<TD>"+name+"</TD>");
					math=rs.getInt("数学成绩");
					out.print("<TD>"+math+"</TD>");
				out.print("</TR>");
				sum=sum+math;
				number--;
				抽取数目--;
				old_i[j]=i;
				j++;
			}
		out.print("</Table>");
		out.print("平均成绩是："+sum/k);
		con.close();
	}catch(SQLException e1){}
%>

</FONT>
</BODY>
</HTML>

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