Riversatile

And if you want to store in a file SQL queries that you run on the WordPress Dashboard, put this code into your functions.php in your Theme folder :
(This will not showing number of SQL queries in the footer. This just place the script in the Admin footer)

/*
#######################################
Store in a file SQL queries I run via my WordPress Dashboard
#######################################
*/
add_action('admin_footer', 'my_admin_footer_function');
function my_admin_footer_function() {
    // Custom Time Zone
    date_default_timezone_set('Europe/Paris');
    // Define the file name and location in the variable $log_file
    // Below, the path correspond to http://your-site/dashboard-queries.txt
    $log_file = ABSPATH. "dashboard-queries.txt";
    // Store the Date/Time of the page load in the variable $Now
    $Now = date("Y-m-d H:i:s");
    // Build the stored informations in the variable $Qdata
    $Qdata = $Now . "," . get_num_queries();
    // Save date of the variable $Qdata in the file $log_file
    file_put_contents($log_file, PHP_EOL . $Qdata , FILE_APPEND);
}

UP please !

Finaly, I found the solution by myself after more than 30 different websites !
If this may help to some. The following code allows your WordPress to store [The page load Date/Time, number of SQL queries on that page] in separated rows !

<?php
    // Custom Time Zone
    date_default_timezone_set('Europe/Paris');
    // Define the file name and location in the variable $log_file
    // Below, the path correspond to http://your-site/queries.txt
    $log_file = ABSPATH. "queries.txt";
    // Store the Date/Time of the page load in the variable $Now
    $Now = date("Y-m-d H:i:s");
    // Build the stored informations in the variable $Qdata
    $Qdata = $Now . "," . get_num_queries();
    // Save date of the variable $Qdata in the file $log_file
    file_put_contents($log_file, PHP_EOL . $Qdata , FILE_APPEND);
?>

Now, I just have to wait some hours, and I should be able to see why and how my site exceeds more than 50000 querie an hour.
We can also include Host IP address in the rows if we want to know if ban a suspicious IP address is necessary to limit queries.