ขอสอบถามเรื่อง Search ข้อมูลอ่าครับ คำค้นหายไป หรือว่าใส่เงื่อนไขผิดอ่าครับ

<p>&nbsp;</p>
<form id="searchResearchYear" name="searchResearchYear" method="post" action="">
  <p align="center" class="headtableTextTahoma11ptBold"><img src="img/BTTitleSearchRe.png" width="500" height="50" /></p>
  <table width="700" border="0" align="center" cellpadding="3" cellspacing="2" class="TextboxBorderSoild">
    <tr align="center">
      <td width="96" class="headtableTextTahoma11ptBoldBG">ค้นหาจาก</td>
      <td width="156" class="headtableTextTahoma11ptBoldBG"><span class="contenttableBG">
        <select name="field" id="field">
          <option value="" selected="selected">-------- กรุณาเลือก --------</option>
          <option value="research_name">ชื่องานวิจัย</option>
          <option value="research_year">ปีการศึกษา</option>
              </select>
      </span></td>
      <td width="50" class="contenttableBG"><span class="headtableTextTahoma11ptBoldBG">คำค้น</span></td>
      <td width="250" class="contenttableBG"><input name="keyword" type="text" id="keyword" size="35" /></td>
      <td width="106" class="contenttableBG"><input name="search" type="submit" id="search" value="ค้นหา" />
        <input name="cancel2" type="reset" id="cancel2" value="ยกเลิก" /></td>
    </tr>
  </table>
  <div align="center">
    <p>
      <?php
	  
$maxRows_research_query = 10;
$pageNum_research_query = 0;
if (isset($_GET['pageNum_research_query'])) {
  $pageNum_research_query = $_GET['pageNum_research_query'];
}
$startRow_research_query = $pageNum_research_query * $maxRows_research_query;

mysql_select_db($database_connect, $connect);

$field = $_POST[field];
$_SESSION[field] = $field;
$key = $_POST[keyword];
$_SESSION[keyword] = $key;
if($_SESSION[field]=="" & $_SESSION[keyword]=="")
{
	$query_research_query = "SELECT * FROM research";
	$query_limit_research_query = sprintf("%s LIMIT %d, %d", $query_research_query, $startRow_research_query, $maxRows_research_query);
$research_query = mysql_query($query_limit_research_query, $connect) or die(mysql_error());
$row_research_query = mysql_fetch_assoc($research_query);
}
if($_SESSION[field]=="research_name" & $_SESSION[keyword]!="")
{
	$query_research_query = "SELECT * FROM research where research_name like '%$_SESSION[keyword]%'";
		$query_limit_research_query = sprintf("%s LIMIT %d, %d", $query_research_query, $startRow_research_query, $maxRows_research_query);
$research_query = mysql_query($query_limit_research_query, $connect) or die(mysql_error());
$row_research_query = mysql_fetch_assoc($research_query);
}
else if($_SESSION[field]=="research_year" & $_SESSION[keyword]!="")
{
	$query_research_query = "SELECT * FROM research where research_year like '%$_SESSION[keyword]%' ";
		$query_limit_research_query = sprintf("%s LIMIT %d, %d", $query_research_query, $startRow_research_query, $maxRows_research_query);
$research_query = mysql_query($query_limit_research_query, $connect) or die(mysql_error());
$row_research_query = mysql_fetch_assoc($research_query);
}
else
{
	$query_research_query = "SELECT * FROM research";
		$query_limit_research_query = sprintf("%s LIMIT %d, %d", $query_research_query, $startRow_research_query, $maxRows_research_query);
$research_query = mysql_query($query_limit_research_query, $connect) or die(mysql_error());
$row_research_query = mysql_fetch_assoc($research_query);
} 





echo $query_research_query;
$nub = mysql_num_rows(mysql_query($query_research_query));
echo $nub;
if (isset($_GET['totalRows_research_query'])) {
  $totalRows_research_query = $_GET['totalRows_research_query'];
} else {
  $all_research_query = mysql_query($query_research_query);
  $totalRows_research_query = mysql_num_rows($all_research_query);
}
$totalPages_research_query = ceil($totalRows_research_query/$maxRows_research_query)-1;

$queryString_research_query = "";
if (!empty($_SERVER['QUERY_STRING'])) {
  $params = explode("&", $_SERVER['QUERY_STRING']);
  $newParams = array();
  foreach ($params as $param) {
    if (stristr($param, "pageNum_research_query") == false && 
        stristr($param, "totalRows_research_query") == false) {
      array_push($newParams, $param);
    }
  }
  if (count($newParams) != 0) {
    $queryString_research_query = "&" . htmlentities(implode("&", $newParams));
  }
}
$queryString_research_query = sprintf("&totalRows_research_query=%d%s", $totalRows_research_query, $queryString_research_query);
?>
</p>
    <p>&nbsp;    </p>
  
        <table border="1" cellpadding="0" cellspacing="0">
      <tr>

        <td bgcolor="#66CCFF"><div align="center"><strong>&#3594;&#3639;&#3656;&#3629;&#3591;&#3634;&#3609;&#3623;&#3636;&#3592;&#3633;&#3618;</strong></div></td>
        <td bgcolor="#66CCFF"><div align="center"><strong>&#3611;&#3637;&#3585;&#3634;&#3619;&#3624;&#3638;&#3637;&#3585;&#3625;&#3634;</strong></div></td>
        <td bgcolor="#66CCFF"><div align="center"><strong>&#3588;&#3603;&#3632;&#3623;&#3636;&#3594;&#3634;&#3649;&#3621;&#3632;&#3612;&#3641;&#3657;&#3610;&#3619;&#3636;&#3627;&#3634;&#3619;</strong></div></td>
      </tr>
      <?php  do {
	  
	 
	   ?>
        <tr>

          <td bgcolor="#FFFFFF"><div align="center"><a href="/tcc_research_innovation/file_research/<?php echo $row_research_query['research_file']; ?>"><?php echo $row_research_query['research_name']; ?></a></div></td>
          <td bgcolor="#FFFFFF"><div align="center"><?php echo $row_research_query['research_year']; ?></div></td>
          <td bgcolor="#FFFFFF"><div align="center">
            <? $query_faculty = "SELECT * FROM faculty_executives where faculty_executives_id =".$row_research_query['faculty_executives_id'];
						$faculty_query = mysql_query($query_faculty, $connect) or die(mysql_error());
					$row_faculty_query = mysql_fetch_assoc($faculty_query);
					echo $row_faculty_query['faculty_executives_name'];
					?>
          </div></td>
        </tr>
        <?php  } while ($row_research_query = mysql_fetch_assoc($research_query));?>
</table>
        <p>
		<?
			$sum=ceil($nub/$maxRows_research_query);
			$suma=0;
			$last_pd=$nub-$maxRows_research_query;
			echo "หน้า";
			for($a=1;$a<=$sum;$a++)
			{
			?>
		  <a href='search_research.php?pageNum_research_query=<? echo "$suma"; ?>'><? echo "$a"; ?></a>
		  <? $suma=$suma+1;
			} 
			$suma-=1;
		    ?>
        </p>
  </div>
</form>