cloudnet server

<?php
    $host = 'localhost';
    $username = 'username';
    $password = 'password';
    $conn=mysqli_connect($host,$username,$password,'cloudnet') or die("Unable to Connect");
    if(empty($_POST['key'])) {//get or remove
        if(empty($_POST['get'])) {//remove
            mysqli_query($conn, "DELETE FROM ".$_POST['remove']." WHERE ".$_POST['type']."='" . $_POST['filter']."'");
            echo "success";
        }else{//get
            if(empty($_POST['filter'])) {//no filter
                $result = mysqli_query($conn, "SELECT * FROM ".$_POST['get']);
                echo "{";
                if(mysqli_num_rows($result) > 0){
                    while($row = mysqli_fetch_assoc($result)){
                        echo "{header='" . $row['header'] . "',message='" . $row['message'] . "',dummy='" . $row['dummy'] . "',},";
                    }
                }
                echo "}";
            }else{//filter
                $result = mysqli_query($conn, "SELECT * FROM ".$_POST['get']." WHERE ".$_POST['type']."='" . $_POST['filter']."'");
                echo "{";
                if(mysqli_num_rows($result) > 0){
                    while($row = mysqli_fetch_assoc($result)){
                        echo "{header='" . $row['header'] . "',message='" . $row['message'] . "',dummy='" . $row['dummy'] . "',},";
                    }
                }
                echo "}";
            }
        }
    }else{//create or store
        if(empty($_POST['header'])) {//create
            if(mysqli_num_rows(mysqli_query("SHOW TABLES LIKE '".$_POST['key']."'"))==0) {
                mysqli_query($conn, "CREATE TABLE ".$_POST['key']."(header VARCHAR(50) NOT NULL,message VARCHAR(360) NOT NULL,dummy VARCHAR(50) NOT NULL)");
            }
            echo "success";
        }else{//store
            mysqli_query($conn, "INSERT INTO ".$_POST['key']."(header,message,dummy) VALUES ('".$_POST['header']."','".$_POST['message']."','".$_POST['dummy']."')");
            echo "success";
        }
    }
?>