"No database selected" error with mysql_query [duplicate] - php

Question

This question already has answers here:
MYSQL PHP No Database Selected - Can't Find Error
(2 answers)
Closed 7 years ago.
Here is my php code
<?php
error_reporting(E_ALL);
class ll{
function ll(){
include "sql.php";
}
function getUser($ID) {
$sql="select * FROM users where ID=$ID";
$res = mysql_query($sql) or die (mysql_error());
$obj = mysql_fetch_object($res);
return $obj;
}
function setOfflineALL() {
$sql="update users set online=0";
mysql_query($sql);
}
}
$services = new ll();
$services->setOfflineALL(); // THIS WORKS !
$services->getUser(1); // THIS GIVES error: No database selected
?>
and sql.php is:
<?php $hostname_con1 = "localhost";
$database_con1 = "db1";
$username_con1 = "root";
$password_con1 = "mypass";
$con1 = mysql_connect($hostname_con1, $username_con1, $password_con1) or trigger_error(mysql_error(),E_USER_ERROR);
mysql_select_db($database_con1);
mysql_set_charset('utf8',$con1);
?>
sql.php is correct (no error)
setOfflineALL works fine (no error)
getUser raises "no database selected error !", however I do select one with mysql_select_db
I do use php5.4
Any clue ?
I also tried:
function getUser($ID) {
$hostname_con1 = "localhost";
$database_con1 = "db1";
$username_con1 = "root";
$password_con1 = "mypass";
$con1 = mysql_connect($hostname_con1, $username_con1, $password_con1) or trigger_error(mysql_error(),E_USER_ERROR);
mysql_select_db($database_con1);
mysql_set_charset('utf8',$con1);
$sql="select * FROM users where ID=$ID";
$res = mysql_query($sql) or die (mysql_error());
$obj = mysql_fetch_object($res);
return $obj;
}
And still have error:
No database selected

Answer 1

You should try this:
mysql_select_db($database_con1, $con1);
And you should give your database variable to your query too:
mysql_query("query", $con1);
And I strongly advise you not to use mysql but use PDO or mysqli
PDO
Mysqli