How to insert values from checkbox using angularjs and php to mysql database?

Question

My Ionic app Code is following:

    <label class="item item-input item-floating-label light">
        <span class="input-label">Date</span>
        <input type="date" placeholder="Date" ng-model="data.date" style="color: white;">
    </label>
    <div class="list card" style="background:#3CB371;" ng-repeat="student in students">
        <ion-checkbox class="checkbox-balanced" ng-model="data.reg_no" ng-checked="data.reg_no" style="color: white;">{{student.reg_no}}</ion-checkbox>
    </div>

//sends the data to server Add

app.js Code is following:

.controller('TakeAttendanceCtrl', function($scope, $http, ionicMaterialInk){

    $scope.add = function(data) {
        $http({
                method: 'post',
                url: host + 'api.php?take_attendance',
                params: data
            })
            .then(
                function(suc) {
                    if (confirm("Attendance updated.")) {
                        window.location.href = "home.html";
                    } else {
                        window.location.reload();
                    }
                },
                function(err) {});
    }
})

and my server side code is following: (api.php)

 include "library.php";
if(isset($take_attendance))
{

    insert("attendance","'','$date', '$reg_no'");
}

and the library.php file is this:

header("Access-Control-Allow-Origin:*");
extract($_REQUEST);
mysql_connect("localhost","root","");
mysql_select_db("sis"); 
function insert($table,$values)
{
    mysql_query("insert into $table values($values)");
    // echo "insert into $table values($values)";
}