สอบถามเรื่องการเพิ่มปีครับ โดย เพิ่มปี หน้าและย้อนหลังได้ ครับ

<table width="904" height="162" border="0" align="center" cellpadding="0" cellspacing="0" bgcolor="" class="tb">
   <thead class="tb">
          <tr class="tb">
            <th width="170" height="28" class="style2">ปีงบประมาณ</th>
            <th width="734" align="left"><input name="txtbudget" type="text" required="required" id="txtname3" OnKeyPress="return chkNumber(this)" value="25" size="4" maxlength="4" minlength="3"/>
              <span class="style2">(เช่น :25xx)</span></th>
            </tr>
    </thead>
          <tr class="tb"> 
            <td height="31" class="style2">จำนวนงบประมาณ</td>
            <td><input name="txtmoney" type="text" required="required" id="txtname5" OnKeyPress="return chkNumber(this)"/>
            บาท</td>
          </tr>
</table>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<?php
require('connect.php');
?>



<?php
$txtbudget01 = $_POST['txtbudget'];
$date = date("Y") ;
$yearthai   = $date+543 ;
$date01 = date("Y") ;
$yearthai01   = $date01+544 ;
$date02 = date("Y") ;
$yearthai02   = $date02+543 ;
?>
<?php
if($yearthai == $txtbudget01)
	{
$txtbudget = $_POST['txtbudget'];
$txtmoney = $_POST['txtmoney'];
$sql ="insert into tbbudgetyear (
BudgetyearID,Budgetyear,Budgetyearmoney)values  
('NULL','$txtbudget','$txtmoney')";
$result=mysql_query($sql,$conn);
	echo "<script language='javascript'>alert('บันทึกข้อมูลเรียบร้อยแล้ว');</script>";
	//echo "<meta http-equiv='refresh' content='0;url=selectlistbudget.php?year=$txtbudget' />";

	}elseif($yearthai01 == $txtbudget01)
	{
$txtbudget = $_POST['txtbudget'];
$txtmoney = $_POST['txtmoney'];
$sql ="insert into tbbudgetyear (
BudgetyearID,Budgetyear,Budgetyearmoney)values  
('NULL','$txtbudget','$txtmoney')";
$result=mysql_query($sql,$conn);
	echo "<script language='javascript'>alert('บันทึกข้อมูลเรียบร้อยแล้ว');</script>";
	//echo "<meta http-equiv='refresh' content='0;url=selectlistbudget.php?year=$txtbudget' />";

	}elseif($yearthai02 > $txtbudget01)
	{
$txtbudget = $_POST['txtbudget'];
$txtmoney = $_POST['txtmoney'];
$sql ="insert into tbbudgetyear (
BudgetyearID,Budgetyear,Budgetyearmoney)values  
('NULL','$txtbudget','$txtmoney')";
$result=mysql_query($sql,$conn);
	echo "<script language='javascript'>alert('บันทึกข้อมูลเรียบร้อยแล้ว');</script>";
	//echo "<meta http-equiv='refresh' content='0;url=selectlistbudget.php?year=$txtbudget' />";

	}
	else
	{
	echo "ปีงบประมาณนี้ผิดรูปแบบ"	;
		}
	
	
?>