如何将str_replace与$row链接一起使用

如何使用带有$row链接的str_replace现在我的链接显示为这样的

example.com/view.php?category=laptop&model=dell i5

我想要这个

example.com/view.php?category=laptop&model=dell_i5

这是一个链接代码

<a href='"detail.php?category=" . $row['category'] . "&model=" . $row['model'] ."'" >

那么我如何使用str_replace和链接".$row['model']。"

请帮我解决这个问题

完整代码

<?php
        //connect to database
     mysql_connect('localhost','user','password');
     mysql_select_db('newalldata');

$page = (empty($_GET['page'])) ? 1 : $_GET['page'];
$max_results = 6;
$from = (($page * $max_results) - $max_results);

if(empty($_POST)) {
              $query = "SELECT * FROM alldata  LIMIT $from, $max_results";
} 
$result = mysql_query("SET NAMES utf8"); //the main trick
$result = mysql_query($query) or die(mysql_error());
$rows = mysql_num_rows($result);
$count=0;
while($row = mysql_fetch_array($result))
    {
        if($count%6==0)
        {
        echo "<tr/>";
        echo "<tr>";
        }

        echo "<td><hr><div class='style99' align='center'><a href='"detail.php?category=" . $row['category'] . "&model=" . $row['model'] ."'" class='"style2'"><img src='/media/image.php?width=200&amp;height=210&amp;image=/media/" . $row['photo'] . "'  title=". $row['price'] ."  alt=". $row['model'] ." style='FILTER: alpha(opacity=100);-moz-opacity: 1.0; opacity: 1.0;' onmouseover=BeginOpacity(this,100,40) onmouseout=EndOpacity(this,100)></a><p><font   color='#3366FF'>" . $row['category'] . "</font></p><p><font   color='#3366FF'>" . $row['model'] . "</font></p><p><font   color='#336600'>" . $row['price'] . "</font></p><div></td>";
        $count++;

}


?>