date2.php

<?php
    require_once 'config/db_config.php';
 
	$sql = "SELECT *, DATE_FORMAT(timestamp, '%Y-%c-%e') selector FROM events WHERE DATE_FORMAT(timestamp, '%Y-%c') = '".$_POST['d']."' ORDER BY DATE_FORMAT(timestamp, '%Y%c%e'), id DESC";
	$query = mysqli_query($link, $sql);
 
    if (mysqli_num_rows($query) > 0){
    	$data = array(); $index = 0;
    	while ($recset = mysqli_fetch_array($query)){
    		$data[$index] = $recset;
    		$index++;
    	}
    	$data['rows'] = mysqli_num_rows($query);
    	echo json_encode($data);
    }
?>

script.js

    for (i = 1; i <= days_number; i++) {
        if (m === actual_m && diap === actual_d) {
            tbody.append("<td id=\"" + y + "-" + m + "-" + diap + "\" class=\"actual\"><span><a href=\"#myModal\" role=\"button\" class=\"days\" data-toggle=\"modal\">" + diap + "</a></span></td>");
        }
        else {
            tbody.append("<td id=\"" + y + "-" + m + "-" + diap + "\"><span><a href=\"#myModal\" role=\"button\" class=\"days\" data-toggle=\"modal\">" + diap + "</a></span></td>");
        }

        if (i % 7 === 0) { tbody.append("</tr><tr>"); }

        if (diap === days_number) { break; }

        diap++;
    }

    $.ajax({
        dataType: "json",
        url: "./php/date2.php",
        type: "POST",
        data: { d: y + "-" + m },
        success: function(data) {
            // Esto de data_j es algo que empece a armar, tratando de armar arrays segun la fecha
            data_j = [];
            for (i = 0; i < data['rows']; i++){
                if (data[i]['selector'] == data[i]['selector']) {
                    data_j.push({ i: data[i]['selector']});
                }
            }
            console.log(data_j);
            // *****
            
            console.log(data);
            $("<span class=\"badge badge-info\">" + data[0].id + "</span>").prependTo($("#" + data[0]['selector']));
            // success
        }
    });