Books site search has duplicates output

Hi
I have use the help on this site on, developing a site search engine with PHP and MYSQL by Mitchell Harper.

I redo the scripts to do a search for books. The problem was that they is only one output result eventhough they should be two. so I took out the "$books = array_unique($books);" from the scripts and it shows the correct results. However if i were to put two keywords to search, i would get a duplicate. If I keep the "$books = array_unique($books);" it still does the duplicates when two or more keywords are entered. Could anyone help. Thanks.

this is the codes
---------------------------------------------------------------------------------

function doSearch($searchfield)
{
$arrWords = explode(" ", $searchfield);

if(sizeof($arrWords) == 0 || $searchfield == "")
{
echo "You didn't enter any keywords<br>";
}
else
{

// Connect to the database
$conn = db_connect();
for($i = 0; $i < sizeof($arrWords); $i++)
{
$query = "select book_id from searchWords where word = '{$arrWords[$i]}'";
$result = mysql_query($query);
if(mysql_num_rows($result) > 0)
{
// Get the id's of the articles
$row = mysql_fetch_array($result);
$arrIds = explode(",", $row[0]);
$arrWhere = implode(" OR book_id = ", $arrIds);
$aQuery = "select isbn, title, left(description, 100) as summary from books where book_id = " . $arrWhere;

$aResult = mysql_query($aQuery);
$count = 0;
$books = array();

if(mysql_num_rows($aResult) > 0)
{
while($aRow = mysql_fetch_array($aResult))
{
$books[$count] = array ("isbn" => $aRow["isbn"],"title" => $aRow["title"],"summary" => $aRow["summary"]);
$count++;
}
}
if(isset($books))
{
//$books = array_unique($books);

echo "<b>" . sizeof($books);
echo (sizeof($books) == 1 ? " book" : " books");
echo " found:</b><br>";

foreach($books as $a => $value)
{
?>

<a href="show_book.php?isbn=<?php echo $books[$a]["isbn"]; ?>">
<b><u><?php echo $books[$a]["title"]; ?></u></b>
</a>

<br><?php echo $books[$a]["summary"] . "..."; ?>
<br>

<A class=NArialSG href="show_book.php?isbn=<?php echo $books[$a]["isbn"]; ?>">
Click to view book
</a>

<br><br>
<?php
}
}
}else {

echo "No results found for '$searchfield'<br>";
}

}
}
}

?>
--------------------------------------------------------------------------------
MySQL searchWord table:
1. Macroeconomics Sixth Edition - assign keywords - economics
2. Essential Mathematics for economics & business 2E -assign keywords - economics, mathematics

This is the output results if i were to put in two keywords to search.. keywords:economics mathematics

2 books found:
Macroeconomics Sixth Edition
The sixth edition is in the form of two books, Microeconomics and Macroeconomics, which, f...
Click to view book

Essential Mathematics for economics & business 2E
Essential Mathematics for Economics and Business has become established as one of the leading introd...
Click to view book

1 book found:
Essential Mathematics for economics & business 2E
Essential Mathematics for Economics and Business has become established as one of the leading introd...
Click to view book

try using the like command?? WHERE field LIKE '%$var%'


something like that

Regards
Ben Rowe