Jquery Ajax PHP - 如何确定PHP代码是否成功执行？

Question

So this is my idea, I have a login jquery dialog on my homepage that blocks anyone from using the webpage (behind the login form dialog). I use ajax to submit the information entered to a php page which then checks if the username/password combo exists in the database. If it does, I return true and then close the dialog box (allowing access to the site).

How do I use ajax to check if my php script (from the executed page) returns true or false? I was assuming the success/error options of the ajax function were checking this, but the below code doesnt seem to work.

    $('.login').dialog({
    closeOnEscape: false,
    title: false,
    modal: true,
    width: 'auto',
    show: {effect: "fade", duration: 1500},
    title: 'Login',
    buttons: {
        "Login": function() { 
            $.ajax({
                async: false,
                type: 'POST',
                url: 'sql/login.php',
                success: function(){
                    alert( "Success!");
                },
                error: function(){
                    alert( "Failed!" );
                },
                dataType: "html"
            });
        }
    }
});
$(".login").dialog().parents(".ui-dialog").find(".ui-dialog-titlebar").remove(); 

Answer 1

What I did was to put an echo at the end of my php with the variabel that is put in true or false, the I did this function inside the success option it is like this:

success: function(response){
                    if(response){
                            alert( "Success!");
                            }else{
                            alert( "Failed!" );
                                 }

                    }

This worked for me, and you can put this in the php

if($myvar){
$anothervar=1;
}else{
$anothervar=0;
}
echo $anothervar;

so you can do this:

success: function(response){
                    if(response==1){
                            alert( "Success!");
                            }else{
                            alert( "Failed!" );
                                 }

                    }

this is the way that I do it and it works fine Hope it is useful