ช่วยดูหน่อยว่าต้องแก้ยังไง ติดปัญหาในการเชื่่อมตารางอะ

<?
include("../../Connections/db_member.php"); 
$strSQL = "SELECT * FROM company_information, student_information WHERE company_information.company_name = student_information.company_name";
	if($_POST["ddlSelect"] != "" and  $_POST["txtKeyword"]  != '')
	{
	  $strSQL .= " AND (".$_POST["ddlSelect"]." LIKE '%".$_POST["txtKeyword"]."%' ) ";
	}	


	$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");
	$Num_Rows = mysql_num_rows($objQuery);
  $Per_Page = 15;   // Per Page

	$Page = $_GET["Page"];
	if(!$_GET["Page"])
	{
		$Page=1;
	}

	$Prev_Page = $Page-1;
	$Next_Page = $Page+1;

	$Page_Start = (($Per_Page*$Page)-$Per_Page);
	if($Num_Rows<=$Per_Page)
	{
		$Num_Pages =1;
	}
	else if(($Num_Rows % $Per_Page)==0)
	{
		$Num_Pages =($Num_Rows/$Per_Page) ;
	}
	else
	{
		$Num_Pages =($Num_Rows/$Per_Page)+1;
		$Num_Pages = (int)$Num_Pages;
	}


	$strSQL .=" order  by company_name asc LIMIT $Page_Start , $Per_Page";
	$objQuery  = mysql_query($strSQL);

	?>
          <table width="100%" border="1" cellpadding="1" cellspacing="1">
            <tr>
              <th width="35%"> <div align="center"><strong>ชื่อบริษัท</strong></div></th>
              <th width="50%"><strong>สถานที่อยู่</strong></th>
              <th width="15%"> <strong>เวลา</strong></th>
            </tr>
<?
$i = 0;
while($objResult = mysql_fetch_array($objQuery))
{
$i++;
?>
            <tr>
              <td width="35%" align="left" valign="top"><a href="Print_invoice1.php?company_name=<?=$objResult["company_name"];?>">
                <?=$objResult["company_name"];?>
              </a></td>
              <td width="50%" align="left"><?=$objResult["Location"];?></td>
              <td width="15%" align="center" valign="top"><?=$objResult["company_information_day"];?></td>
            </tr>
<?
}
?>