数据库问题请教专家，嘿嘿
- Java code
<html> <head> </head> <body> <h2 align="center">你准备修改的学生的成绩是：</h2> <table align="center" width="80%" border="1"> <tr> <td align="center">学号</td> <td align="center">语文成绩</td> <td align="center">数学成绩</td> <td align="center">英语成绩</td> <td align="center">计算机成绩</td> </tr> <tr><td align="center">333</td> <td align="center">60</td> <td align="center">58</td> <td align="center">74</td> <td align="center">49</td> </table> <h2> 输入新值：</h2><br/> <form action="change.jsp"> <table align="center" width="80%" border="1" height="77" ><tr> <td align="center">语文成绩</td> <td align="center">数学成绩</td> <td align="center">英语成绩</td> <td align="center">计算机成绩</td> </tr> <tr> <td align="center"><input type="text" name="chinese" /></td><td align="center"><input type="text" name="math"/></td><td align="center"><input type="text" name="english"/></td><td align="center"><input type="text" name="computer"/></td> </tr> </table><br/><div align="center"> <input type="submit"value="提交修改" ></div></form> </body></html>
如果四个值全部有的话，可以修改，只要一个为空，则会出现错误，求解
- Java code
DBHelper db=new DBHelper(); String ids= (String)session.getAttribute("id"); String[] s={"chinese","math","english","computer"}; for(int i=0;i<s.length;i++) { if(request.getParameter(s[i])!=null){ String ss=request.getParameter(s[i]); if(ss!=null ) { int fe=Integer.parseInt(ss); String sql="update grade set "+s[i]+"="+fe+" where id="+ids; db.exeUpdate(sql); out.print("<script>alert('修改成功')</script>"); } } } %> </body>[解决办法]