通过ajax调用php mySQL更新

I think this is simple question. I'm new to jQuery. I'm trying to make script, so that when you click on image, ajax will call php file which will update mySQL database.

My script:

<script>
function update(){      
        var request = $.ajax({
        url: "insert.php",
        type: "GET",            
        dataType: "html"
    });

    request.done(function(msg) {
        $("div.recen").html(msg);          
    });

    request.fail(function(jqXHR, textStatus) {
        alert( "Request failed: " + textStatus );
    });
}; 
</script>

HTML:

<div class="recen">
            <img src="./smile.png" class="pic" onclik="update()" /> 
</div>

PHP file:

<?php
$var='123';

$url='localhost';
$user='root';
$password='';

$sql=mysql_connect($url,$user,$password);
mysql_select_db('database');

$query="UPDATE table SET var='".$var."';";
if(mysql_query($query)) echo '<b>Done.</b>';
else echo mysql_error();
?>

For some reason, there is absolutely no response. Database remains the same and html page doesn't change a bit. Is there something wrong with the code, or I just can't update database through ajax?

i think somthing wrong in your query

try this

   $query="UPDATE table SET var='".$var."' ";
                                          ^^----remove this `;`

change this

 if(mysql_query($query)) echo '<b>Done.</b>';
 else echo mysql_error();

to

 if(mysql_query($query)){ echo '<b>Done.</b>';}
 else {echo mysql_error();}

there is no onclik in javascript instead use onClick

You have a typo in your HTML code. Your attribute should be onclick not onclik.

<img src="./smile.png" class="pic" onclick="update()" />