请问多条更新记录提交如何写SQL

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script><script src="js/slide_up.js"></script><meta charset="UTF-8"><?phprequire("inc/pdo.php");$select=$dbc->prepare("select id,slide_name,slide_href,slide_img from zt_slide");$select->execute();while($row=$select->fetch()){ ?>焦点图管理<form method="post" action="12.php"enctype="multipart/form-data"><input type="text" id='id' name="id[]" value="<?php echo $row['id'];?>"><br/>名称<input type='text' id='slide_name' name="slide_name[]" value="<?php echo $row['slide_name'];?>"><br/>图片上传<input type='text' id='img'name="img[]" value="<?php  echo $row['slide_img']; ?>"><input type="file" id="file"name="file[]"><br/>文章地址<input type='text' id='slide_href' name="slide_href[]" value="<?php  echo $row['slide_href']; ?>"><br/></div><?php }?><div id='insert_zt' class='slide'><input type="hidden" name="action" value="focus">名称<input type='text' id='slide_name' name="slide_name[]" ><br/>图片上传<input type='file' id='file' name="file[]"><br/>文章地址<input type='text' id='slide_href' name="slide_href[]"><br/></div><button id="insert">增加一项</button><input type="submit" id="submit"></form>

<?php$id=$_POST['id'];$name=$_POST['slide_name'];$img=$_POST['img'];$href=$_POST['slide_href'];foreach($id as $id1)    {        echo $id1."<br>";    }    foreach($name as $slide_name)    {        echo $slide_name."<br>";    }	foreach($img as $slide_img)    {        echo $slide_img."<br>";    }	foreach($href as $slide_href)    {        echo $slide_href."<br>";    }//$sql="UPDATE tab SET  slide_name=$slide_name,img=$slide_img, WHERE id = $id"; 	请问SQL应该怎么写??>