JAVA学生管理系统 第7页
import java.util.*;
import java.sql.*;
import javax.swing.*;
/**
* 用来保存成绩查询方面的类
*/
public class csBean {
String sql;
ResultSet rs;
Vector tempvector=new Vector(1,1);
String cNum;
String sNum;
float grade;
int colNum;
/**
* 添加学生的选课信息
*/
public void csAdd(String cnum, String snum){
Database DB = new Database();
this.cNum = cnum;
this.sNum = snum;
sql = "insert into sc(cnum,snum) values ("+Integer.parseInt(cNum)+","+Integer.parseInt(sNum)+")";
try{
DB.OpenConn();
DB.executeUpdate(sql);
JOptionPane.showMessageDialog(null,"成功添加一条新的纪录！");
}
catch(Exception e){
JOptionPane.showMessageDialog(null, "保存失败", "错误", JOptionPane.ERROR_MESSAGE);
}
finally {
DB.closeStmt();
DB.closeConn();
}
}
/**
* 修改学生的选课成绩
*/
public void csModify(String cnum, String snum, String grade){
Database DB = new Database();
this.cNum = cnum;
this.sNum = snum;
try{
this.grade = Float.parseFloat(grade);
}
catch(Exception e){
JOptionPane.showMessageDialog(null, "成绩输入错误", "错误", JOptionPane.ERROR_MESSAGE);
return;
}
sql = "update sc set grade = "+grade+" where snum = "+Integer.parseInt(sNum)+" and cnum = "+Integer.parseInt(cNum)+" ";
try{
DB.OpenConn();
DB.executeUpdate(sql);
JOptionPane.showMessageDialog(null,"成功登记成绩！");
}
catch(Exception e){
System.out.println(e);
JOptionPane.showMessageDialog(null, "登记失败", "错误", JOptionPane.ERROR_MESSAGE);
}
finally {
DB.closeStmt();
DB.closeConn();
}
}
/**
* 根据学号搜索其所选的课程名称
*/
public String[] cNameSearch(String snum){
Database DB = new Database();
this.sNum = snum;
sql = "select * from sc,course where sc.snum = "+Integer.parseInt(sNum)+" and sc.cnum = course.cnum";
String[] cn = null;
int row = 0;
int i = 0;
try{
DB.OpenConn();
rs = DB.executeQuery(sql);
if(rs.last()){
row = rs.getRow();
}
if(row == 0){
cn = null;
}
else{
cn = new String[row];
rs.first();
rs.previous();
while(rs.next()){
cn[i] = rs.getString(5);
i++;
}
}
}
catch(Exception e){
}
finally {
DB.closeStmt();
DB.closeConn();
}
return cn;
}
/**
* 成绩信息综合查询
*/
public String[][] csAllSearch(String snum, int colnum){
this.sNum = snum;
this.colNum = colnum;
Database DB = new Database();
String[][] cn = null;
int row = 0;
int i = 0;
sql = "select * from sc,course,student where sc.snum = "+Integer.parseInt(sNum)+" and sc.cnum = course.cnum and sc.snum = student.snum";
try{
DB.OpenConn();
rs = DB.executeQuery(sql);
if(rs.last()){
row = rs.getRow();
}
if(row == 0){
cn = null;
}
else{
cn = new String[row][colNum];
rs.first();
rs.previous();
while(rs.next()){
cn[i][0] = rs.getString(1);
cn[i][1] = rs.getString(11);
cn[i][2] = rs.getString(2);
cn[i][3] = rs.getString(5);
cn[i][4] = rs.getString(3);
i++; } } }
catch(Exception e){ }
finally { DB.closeStmt(); DB.closeConn(); }
return cn; }}