calling php function from javascript not working

Question

I am trying to perform a php function on click of link

and then get the value from input type text and call perform a select query

so far,

<form name="form" id="form" action="login.php" method="get">
          <h1>Login</h1>
          <div>
            <input name="username" id="username" type="text" class="form-control" placeholder="Username" required="" />
          </div>
          <div>
            <input id="password" type="password" class="form-control" placeholder="Password" required="" />
          </div>
          <div>
            <input id="team" type="text" class="form-control" placeholder="Team" required="" />
          </div>
           <div>
            <a class="btn btn-default submit" type="submit" id="submit" name="submit" onClick='return Logincheck()'>Log in</a>
            <br>
            <br>
            <p class="change_link">Lost your password ??    
            <!-- <a class="reset_pass" href="?sendcode=true">Lost your password?</a> -->
            <a href="#"> Change Password </a>
            </p>
          </div>

so onclick of submit anchor tag it calls LoginCheck javascript i.e

<script type='text/javascript'>
function Logincheck()
{
var user=document.getElementById("username").value;
var pass=document.getElementById("password").value;
var team=document.getElementById("team").value;
}

it successfully performs this task.

but now i have a php file that contains some database connectivity with function that performs select query

not i want to call that file from above javascript function

the php file is dbConnection.php

    <?php
function validateLogin($user,$pass,$team)
{
    $serverName = "server";

    $connectionOptions = array(
    "Database" => "dbName",
    "Uid" => "sa",
    "PWD" => "123456"
    );
//Establishes the connection
$conn = sqlsrv_connect($serverName, $connectionOptions);

    $tsql= "SELECT Password,Name,Team FROM Login where Username=?;";
    $params = array($user);
    $getResults= sqlsrv_query($conn, $tsql,$params);
    //echo ("Reading data from table");
    if ($getResults == FALSE)
        die(FormatErrors(sqlsrv_errors()));
    while ($row = sqlsrv_fetch_array($getResults, SQLSRV_FETCH_ASSOC)) {
        $password=$row['Password'];
        $empName=$row['Name'];
        $temaname=$row['Team'];

        if($password==$pass && $team==$temaname)
        {
            echo '<script>
            alert("Login Success !!!!")
            var newURL = location.href.split("?")[0];
            window.history.pushState(null, null, window.location.pathname);
            </script>';
        }
        else
        {
            echo '<script>
            alert("Login Faild !!!!")
            var newURL = location.href.split("?")[0];
            window.history.pushState(null, null, window.location.pathname);
            </script>';
        }

    }
    sqlsrv_free_stmt($getResults);
}
?>

but i dont know how to call the validateLogin(user,pass,team) of above php file from the javascript of my first file

i was trying below code but no luck,

<script type='text/javascript'>
function Logincheck()
{
var user=document.getElementById("username").value;
var pass=document.getElementById("password").value;
var team=document.getElementById("team").value;
alert("hi");
var result=
"<?php
include 'dbConnection.php';
echo validateLogin("2012","hcca123@","BFL");
?>";

alert(result);
}

but i think i am doing something wrong, but not getting the cause. plz help