jsp插入Mysql数据库的全是NUll，而且我的数据库中字段不允许为空(驱动啊，数据库连接啊，都是对的）。求高手指点哈，我都挣扎好几天啦
javabean：
package company;

import java.sql.*;

public class jiaofeijilu {

public String comid;
public String renshu;
public String jishu;
public String feilv;
public String paysum;
public String shenbaodate;
public String jingbanren;

public String getComid() {
return comid;
}

public void setComid(String comid) {
this.comid = comid;
}

public String getRenshu() {
return renshu;
}

public void setRenshu(String renshu) {
this.renshu = renshu;
}

public String getJishu() {
return jishu;
}

public void setJishu(String jishu) {
this.jishu = jishu;
}

public String getFeilv() {
return feilv;
}

public void setFeilv(String feilv) {
this.feilv = feilv;
}

public String getPaysum() {
return paysum;
}

public void setPaysum(String paysum) {
this.paysum = paysum;
}

public String getShenbaodate() {
return shenbaodate;
}

public void setShenbaodate(String shenbaodate) {
this.shenbaodate = shenbaodate;
}

public String getJingbanren() {
return jingbanren;
}

public void setJingbanren(String jingbanren) {
this.jingbanren = jingbanren;
}



public Connection conn;
public Statement smt;
public ResultSet rs;
public String sql2="insert into compayrecord(comid,renshu,jishu,feilv,paysum,shenbaodate,jingbanren) values ('"+comid+"','"+renshu+"','"+jishu+"','"+feilv+"','"+paysum+"','"+shenbaodate+"','"+jingbanren+"')";
//public String sql1="select * from compayrecord where comid='"+comid+"'";

public void add(){
try{Class.forName("com.mysql.jdbc.Driver");

}
catch(ClassNotFoundException e){
System.out .print(""+e);
}
try{
conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/system","root","123");
smt=conn.createStatement();
//rs=smt.executeQuery(sql1);
/*if(!rs.next()){*/
smt.executeUpdate(sql2);  
 
 
 
//}

}
catch(Exception ee){
ee.printStackTrace();
}


}
}





jsp页面：jiaofeishenbao.jsp
 <form action="shenbaosuccess.jsp" method="post" name="myform">
  <table width="80%" height="493" border="1" align="center" cellspacing="0" bordercolor="#89AB00">
  <tr>
  <td height="79" colspan="5"><div align="center" class="STYLE14">缴费申报表</div></td>
  </tr>
  <tr>
  <td width="16%" height="45">单位ID：<br></td>
  <td colspan="4"><input type="text" name="comid" id="textfield4"></td>
  </tr>
  <tr>
  <td height="46">缴费人数：</td>
  <td colspan="4"><label> 
  <input type="text" name="renshu" id="textfield"> 
  （<span class="STYLE17">人数必须和参保登记的人数一致</span>）</label></td>
  </tr>
  <tr>
  <td height="48">缴费基数：</td>