Free! - How to build a PHP Search Engine

Introduction or a tale of how easy a search engine could work

Five years ago your site may have had five or six pages. However, over the time it has grown and one day you wake up with 2 GB of content, more than a thousand links and no way to sort them by relevance. You need a way for you and your visitors to get information about your services and products faster. A search engine could help you and your site visitors find that precious piece of information on your extensively growing site.

Displaying the results

Now let's display the results. We are going to use a usual loop where we have saved the first results via the $results variable. We are arranging everything nicely in tables. That way our results will be separated and ordered. If no results are found, the page will display the following message:

However, if results are found, the page should look like this:

OK, so back to Search.php where we have inserted our form. Modify the code as follows:

<?PHP
if($results != 0)
{
?>  
   <table border="0" cellspacing="2" cellpadding="2">
  <tr>
    <td width="47%">Results for <?PHP echo "<i><b><font color=#000000>".$search_term."</font></b></i> "; ?></td>
    <td width="53%" align="right" height="22">Results <b>
      <?PHP echo ($first_pos+1)." - ";
      if(($RESULTS_LIMIT + $first_pos) < $results) echo ($RESULTS_LIMIT + $first_pos);
      else echo $results ; ?>
    </b>
      out of <b><?PHP echo $results; ?></b>
      for(<b><?PHP echo sprintf("%01.2f", $time_search); ?></b>)
      seconds </td>
  </tr>
  <tr>
    <form action="" method="GET">
      <td colspan="2" align="center"> <input name="search_term" type="text" value="<?PHP echo $search_term; ?>" size="40">
        <input name="search_button" type="submit" value="Search"> </td>
    </form>
  </tr>
  <?PHP  
    while($row = mysql_fetch_array($sql_result_query))
    {
    ?>
      <tr align="left">
        <td colspan="2"><?PHP echo $row['title']; ?></td>
      </tr>
  <?PHP
    }
    ?>
</table>
<?PHP
}
elseif($sql_query)
{
?>
<table border="0" cellspacing="2" cellpadding="0">
    <tr>
        <td align="center">No results for   <?PHP echo "<i><b><font color=#000000>".$search_term."</font></b></i> "; ?></td>
    </tr>
    <tr>
        <form action="" method="GET">
        <td colspan="2" align="center">
            <input name="search_term" type="text" value="<?PHP echo $search_term; ?>">
            <input name="search_button" type="submit" value="Search">
        </td>
        </form>
    </tr>
</table>
<?PHP
}
?>

Sorting into pages

Our final step is to show the number of result pages. We are calculating how many results the SQL query has returned. We start by calculating the first position in order to place it in relevance. If the maximum number of results is exceeded the algorithm creates a forward button for the user to switch to the next page. We already have defined the maximum number per page via $RESULTS_LIMIT. If the user goes to the second page of the results he can go back and check previous results with a back button. Well, these so called buttons are not really buttons – they are simple ">>" and "<<" signs. Of course feel free to add your own buttons, or even some flash images.

I am also using a PHP function stripslashes in order to escape some quotes. Why? I use it to clean the results from the quotes in the MySQL query. That way the algorithm will not fail if any quotes are inserted.

We can do all this with the following code:

<?PHP
if($first_pos > 0)
{
  $back=$first_pos-$RESULTS_LIMIT;
  if($back < 0)
  {
    $back = 0;
  }
  echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$back' ></a>";
}
if($results>$RESULTS_LIMIT)
{
  $sites=intval($results/$RESULTS_LIMIT);
  if($results%$RESULTS_LIMIT)
  {
    $sites++;
  }
}
for ($i=1;$i<=$sites;$i++)
{
  $fwd=($i-1)*$RESULTS_LIMIT;
  if($fwd == $first_pos)
  {
      echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$fwd '><b>$i</b></a> | ";
  }
  else
  {
      echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$fwd '>$i</a> | ";  
  }
}
if(isset($first_pos) && $first_pos < $results-$RESULTS_LIMIT)
{
  $fwd=$first_pos+$RESULTS_LIMIT;
  echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$fwd ' > >></a>";
  $fwd=$results-$RESULTS_LIMIT;
}
?>
    </td>
  </tr>
</table>

This is the final piece of code in this article.

The next code block contains the entire code for the search engine. I've inserted comments so that you can track the process:

<?PHP
function getmicrotime()
{
    list($usec, $sec) = explode(" ", microtime());
    return ((float)$usec + (float)$sec);
}
//initializing connection to the database
$connection_string = dirname(__FILE__) . "/connectionstring.php";
require_once($connection_string);
//selecting table
mysql_select_db("test") or die ( 'Unable to select database.' );
//max number of results on the page
$RESULTS_LIMIT=10;
if(isset($_GET['search_term']) && isset($_GET['search_button']))
{
      $search_term = $_GET['search_term'];
    if(!isset($first_pos))
    {
        $first_pos = "0";
    }
    $start_search = getmicrotime();
      //initializing MySQL Quary 
    $sql_query = mysql_query("SELECT * FROM news WHERE MATCH(title,article) AGAINST('$search_term')");
    //additional check. Insurance method to re-search the database again in case of too many matches (too many matches cause returning of 0 results)
    if($results = mysql_num_rows($sql_query) != 0)
            {
                $sql =  "SELECT * FROM news WHERE MATCH(title,article) AGAINST('$search_term') LIMIT $first_pos, $RESULTS_LIMIT";
                  $sql_result_query = mysql_query($sql);        
            }
    else
            {
                  $sql = "SELECT * FROM news WHERE (title LIKE '%".mysql_real_escape_string($search_term)."%' OR article LIKE '%".$search_term."%') ";
                  $sql_query = mysql_query($sql);
                  $results = mysql_num_rows($sql_query);
                  $sql_result_query = mysql_query("SELECT * FROM news WHERE (title LIKE '%".$search_term."%' OR article LIKE '%".$search_term."%') LIMIT $first_pos, $RESULTS_LIMIT ");
            }
    $stop_search = getmicrotime();
      //calculating the search time
    $time_search = ($stop_search - $start_search);
}
?>
<?PHP
if($results != 0)
{
?>  
   <!-- Displaying of the results -->
<table border="0" cellspacing="2" cellpadding="2">
  <tr>
    <td width="47%">Results for <?PHP echo "<i><b><font color=#000000>".$search_term."</font></b></i> "; ?></td>
    <td width="53%" align="right" height="22">Results <b>
      <?PHP echo ($first_pos+1)." - ";
      if(($RESULTS_LIMIT + $first_pos) < $results) echo ($RESULTS_LIMIT + $first_pos);
      else echo $results ; ?>
    </b>
      out of <b><?PHP echo $results; ?></b>
      for(<b><?PHP echo sprintf("%01.2f", $time_search); ?></b>)
      seconds </td>
  </tr>
  <tr>
    <form action="" method="GET">
      <td colspan="2" align="center"> <input name="search_term" type="text" value="<?PHP echo $search_term; ?>" size="40">
        <input name="search_button" type="submit" value="Search"> </td>
    </form>
  </tr>
  <?PHP  
    while($row = mysql_fetch_array($sql_result_query))
    {
    ?>
      <tr align="left">
        <td colspan="2"><?PHP echo $row['title']; ?></td>
      </tr>
  <?PHP
    }
    ?>
</table>
<?PHP
}
//if nothing is found then displays a form and a message that there are nor results for the specified term
elseif($sql_query)
{
?>
<table border="0" cellspacing="2" cellpadding="0">
    <tr>
        <td align="center">No results for   <?PHP echo "<i><b><font color=#000000>".$search_term."</font></b></i> "; ?></td>
    </tr>
    <tr>
        <form action="" method="GET">
        <td colspan="2" align="center">
            <input name="search_term" type="text" value="<?PHP echo $search_term; ?>">
            <input name="search_button" type="submit" value="Search">
        </td>
        </form>
    </tr>
</table>
<?PHP
}
?>
<table width="300" border="0" cellspacing="0" cellpadding="0">
      <?php
      if (!isset($_GET['search_term'])) { ?>
    <tr>
        <form action="" method="GET">
        <td colspan="2" align="center">
            <input name="search_term" type="text" value="<?PHP echo $search_term; ?>">
            <input name="search_button" type="submit" value="Search">
        </td>
        </form>
    </tr>
    <?php
      }
      ?>
  <tr>
    <td align="right">
<?PHP
//displaying the number of pages where the results are sittuated
if($first_pos > 0)
{
  $back=$first_pos-$RESULTS_LIMIT;
  if($back < 0)
  {
    $back = 0;
  }
  echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$back' ></a>";
}
if($results>$RESULTS_LIMIT)
{
  $sites=intval($results/$RESULTS_LIMIT);
  if($results%$RESULTS_LIMIT)
  {
    $sites++;
  }
}
for ($i=1;$i<=$sites;$i++)
{
  $fwd=($i-1)*$RESULTS_LIMIT;
  if($fwd == $first_pos)
  {
      echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$fwd '><b>$i</b></a> | ";
  }
  else
  {
      echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$fwd '>$i</a> | ";  
  }
}
if(isset($first_pos) && $first_pos < $results-$RESULTS_LIMIT)
{
  $fwd=$first_pos+$RESULTS_LIMIT;
  echo "<a href='search.php?search_term=".stripslashes($search_term)."&first_pos=$fwd ' > >></a>";
  $fwd=$results-$RESULTS_LIMIT;
}
?>
    </td>
  </tr>
</table>

Do not forget to upload the files connectionstring.php and Search.php in the same directory on your server.

Preview your page and test it. Just open it in your favourite web browser and type in some words. Make sure that your table is filled with some of these words otherwise it will return you that there are no results found.