使用Mamp和MySQL（PHP）“无法连接”

Question

I am trying to access my MySQL database with PHP, but my page keeps returning the error "unable to connect". Here is my code:

echo '<ul>';

$db_host = "localhost";
$db_user = "user";

$db_link = mysqli_connect($db_host, $db_user, $db_password, $db_name)
or die ("Unable to connect");

$sqlQuery = "SELECT u.user_name, m.message_text, m.time_stamp FROM users AS u INNER JOIN messages m ON u.user_id = m.user_id";

$result = mysqli_query($db_link, $sqlQuery);


if($result)
{
 while ($row=mysqli_fetch_assoc($result)) 
  {
    echo "<li>" . $row['message_text'] . "<br>" . $row['user_name'] . "<br>" . $row['time_stamp'] . "</li>
\t\t<hr>";
}
}
else
{
echo '<p>error displaying resultset</p>';
}

mysqli_close($db_link);
echo '</ul>';

Answer 1

It looks like you haven't set $db_password or $db_name, with the latter definitely necessary to connect to the database. The former should also be set assuming you have a password set for the database (you do have a password set, right?) Verify that you have properly set those variables, and then do a var_dump() on the $db_link like this:

echo "<pre>";     //For formatting. 
var_dump($db_link);
echo "</pre>"

This will give you an idea of whether or not you have properly setup the connection object for the database.

UPDATE

SELECT
    u.user_name,
    m.message_text,
    m.time_stamp
FROM
    users AS u
INNER JOIN messages m ON u.user_id = m.user_id

Here's your query, but with the proper formatting. Notice the last line, you have:

INNER JOIN messages m

That stray 'm' isn't necessary, and for the sake of debugging I'd recommend formatting the query like this:

$sqlQuery = "SELECT `user`.user_name, `message`.`message_text`, `message`.time_stamp FROM users INNER JOIN messages ON `users`.user_id = `message`.user_id";

Edit: As an aside, you mentioned that the query gave you a bool(false) when you used var_dump. This tells you that the query is failing and lets you know to start debugging it. (PHP.net)