$strSQL = "SELECT * FROM profilecomputer WHERE (comID LIKE '%".$_GET["txtKeyword1"]."%' AND comSN LIKE '%".$_GET["txtKeyword2"]."%' AND ownTn LIKE '%".$_GET["txtKeyword3"]."%' AND Brand LIKE '%".$_GET["txtKeyword4"]."%' AND TYPE LIKE '%".$_GET["txtKeyword5"]."%' ) ";
ลองเปลี่ยนเป็น Or ดู
$strSQL = "SELECT * FROM profilecomputer WHERE (comID LIKE '%".$_GET["txtKeyword1"]."%' OR comSN LIKE '%".$_GET["txtKeyword2"]."%' OR ownTn LIKE '%".$_GET["txtKeyword3"]."%' OR Brand LIKE '%".$_GET["txtKeyword4"]."%' OR TYPE LIKE '%".$_GET["txtKeyword5"]."%' ) ";