<?php

/**
 * Connect to the database
 *
 * @param string $username
 * @param string $password
 * @param string $dbname
 *
 * @return mysqli the connection to the database
 */
function connect($username, $password, $dbname) {
    $conn = new mysqli("localhost", USERNAME, PASSWORD, DB_NAME);

    if ($conn->connect_errno) {
        echo "Failed to connect to MySQL: (" . $conn->connect_errno . ")" . $conn->connect_error;
    }

    echo 'Connected succesfully to: ' . $conn->host_info . "\n\n";

    return $conn;
}

/**
 * Show the columns and rows of a table
 *
 * @param mysqli $conn a connection to the database
 * @param string $tablename
 *
 * @return void // void significa que esta función no retorna nada
 */
function show_table_data($conn, $tablename) {
    $stmt = $conn->prepare("SELECT * FROM " . TABLENAME);

    if (!$stmt) {
        echo "Prepare failed: (" . $conn->errno . ") " . $conn->error;
    }

    if (!$stmt->execute()) {
        echo "Execute failed: (" . $stmt->errno . ")" . $stmt->error;
    }

    $result = $stmt->get_result();

    while ($item = $result->fetch_object()) { // por cada fila de la tabla
        foreach ($item as $key => $attr) { // por cada clave (columna) y atributo (valor) de cada item de la fila
            echo "$key: $attr\n"; // muestro la clave y el atributo
        }
        echo "\n"; //
    }
}

const USERNAME = '';
const PASSWORD = '';
const DB_NAME = '';
const TABLENAME = '';

$conn = connect(USERNAME, PASSWORD, DB_NAME);
show_table_data($conn, TABLENAME);