在java程序中操作数据库（练习1）

package hanqi;
import java.sql.*;
import java.util.*;
public class Student 
{
    public static void main(String[] args)
    {
        Scanner s=new Scanner(System.in);
        System.out.println("请输入你的四/六级");
        int a=s.nextInt();
        System.out.println("请输入你的身份证号");
        String b=s.next();
        System.out.println("请输入你的准考证号");
        String c=s.next();
        System.out.println("请输入你的姓名");
        String d=s.next();
        System.out.println("请输入你的区域");
        String e=s.next();
        System.out.println("请输入你的成绩");
        int f=s.nextInt();
        
        Connection conn = null;
        try
        {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            String strUrl = "jdbc:oracle:thin:@localhost:1521:ORCL";
            conn = DriverManager.getConnection(strUrl, "text", "123456");
            System.out.println("连接数据库成功");
            
            Statement st=conn.createStatement();
            st.executeUpdate("insert into examstudent  values (se_ff.nextval,"+a+",'"+b+"','"+c+"','"+d+"','"+e+"',"+f+")");
            System.out.println("信息录入成功");
            
            ResultSet rs=null;
            System.out.println("请输入你的身份证号或准考证号,a身份证、b准考证号");
            String a1=s.next();
            if(a1.equals("a"))
            {
                System.out.println("请输入你的身份证号");
                String a11=s.next();
                rs=st.executeQuery("select * from examstudent where IDCard='"+a11+"'");
            }
            else if(a1.equals("b"))
            {
                System.out.println("请输入你的准考证号");
                String a12=s.next();
                rs=st.executeQuery("select * from examstudent where ExamCard='"+a12+"'");
            }
            
            
            while(rs.next())
            {
                String FlowID=rs.getString("FlowID");
                String Type=rs.getString("Type");
                String IDCard=rs.getString("IDCard");
                String ExamCard=rs.getString("ExamCard");
                String StudentName=rs.getString("StudentName");
                String Location=rs.getString("Location");
                String Grade=rs.getString("Grade");
                System.out.println("流水号："+FlowID+" 四/六级："+Type+" 身份证号："+IDCard+" 准考证号；"+ExamCard+" 学生姓名："+StudentName+" 区域；"+Location+" 成绩；"+Grade);
            }
            
            System.out.println("请输入考号，删除该学生的信息");
            String a13=s.next();
            int n=st.executeUpdate("delete from examstudent  where ExamCard='"+a13+"'");
            if(n>0)
            {
                System.out.println("删除成功");
            }
            else
            {
                System.out.println("查无此人");
            }
            st.close();
        } 
        catch (Exception e1) 
        {
            
            e1.printStackTrace();
            
        }
        
         finally 
         {
            try
            {
                conn.close();
            }
            catch (SQLException e1)
            {
                e1.printStackTrace();
            } 
         
         }
    }
}