jQuery无法比较AJAX返回的数据

Question

I am trying to get a form to check if a surname already exists in the database.

It seems like it is working, it checks the database and returns values, eg the number, as a string, of times the surname exists, or 'none' if they did not enter a surname.

The problem I am having is when I try to display the results.

JavaScript:

sName = $('#sName'), sInfo = $("#sInfo");
sName.blur(function() {
        $.ajax({
            type: "POST",
            data: "sName="+$(this).attr("value"),
            url: "check.php",
            beforeSend: function(){
                sInfo.html("<font color='blue'>Checking Surname...</font>");
            },
            success: function(data){
                if(data == "none")
                {
                    sInfo.html("<font color='red'>No Surname Entered</font>");
                }
                else if(data != "0")
                {
                    sInfo.html("<font color='red'>Surname Exists</font>");
                }
                else
                {
                    sInfo.html("<font color='green'>Surname Not Found</font>");
                }
            }
        });
    }); 

check.php:

//database connection stuff

extract($_REQUEST);

if(!empty($sName))
{
    $sql = "SELECT sName FROM student WHERE sName='$sName'";
    $rsd = mysqli_query($DBConnect, $sql) or die('Error: '.mysqli_error($DBConnect));
    $msg = mysqli_num_rows($rsd); 
    mysqli_free_result($rsd);
    mysqli_close($DBConnect);
}
else
{
    $msg = "none";
}
echo $msg;

No matter what the value of data is (eg "1", "2", "0", "none") the sInfo div always displays "Surname Exists".

When I change it to display

else if(data != "0")
                    {
                        sInfo.html("<font color='red'>Surname Exists..."+data+"</font>");
                    }

The result is Surname Exists...0 or Surname Exists...none when it should instead display No Surname Entered or Surname Not Found...

What am I doing wrong?

thanks.

Answer 1

Change the line

data: "sName="+$(this).attr("value"),

to

data: {"sName":$(this).attr("value")},

jquery will format it correctly in the post body