Same select works on console but not in PHP - php

Question

this is getting me mad.
This is the code I'm using right now:
<?php
//open connection to mysql db
$connection = mysqli_connect( "mysql.kit-series.net", "XXXXX", "XXXXXX", "kit_series_net" ) or die( "Error " . mysqli_error( $connection ) );
$connection->set_charset( "utf8" );
//fetch table rows from mysql db
$nombre = $_POST['nombre'];
$select = "SELECT ID FROM wp_qnnpx4_posts WHERE post_type='tvshows' AND post_title = '" . $nombre . "'";
$result = $connection->query( utf8_encode( $select ) );
$result = $result->fetch_assoc();
$id = $result['ID'];
echo $select;
echo $id;
//close the db connection
mysqli_close( $connection );
The result it's the expected if I use the select on console.
The result it's the expected if I use the select in the PHP and the
$nombre varible has no accents.
The result it's the expected if I use
the select in the console and the $nombre varible has accents.
Only when $nombre has accents and is used on the PHP file, the result isn't the expect, and it just return no results.
I printed the select in that case, put it on console, and it works. I dind't know what more to do.
Any idea?

Answer 1

Don't use utf8_encode unless you are processing non-UTF8 strings. From your question and comments it turns out that you are completely on UTF8 (HTML, database, database connection, PHP file encoding), so calling utf8_encode is not only not necessary, it will have averse effects.
As said in an appreciated contribution to the PHP docs on utf8_encode:
If your text is not encoded in ISO-8859-1, you do not need this function. If your text is already in UTF-8, you do not need this function. In fact, applying this function to text that is not encoded in ISO-8859-1 will most likely simply garble that text.