Passing a GET variable back in a query while using mysqli_real_escape_string()

I'm trying to take a variable that's passed in a query string (GET) and then use that variable to do a SELECT based on it...

// Assign query string to a variable while sanitizing it against XSS
$event = ee()->input->get_post('event', TRUE);

// Build query
$sql = "SELECT t.entry_id
    FROM exp_channel_titles t
    LEFT join exp_channel_data d
    ON t.entry_id = d.entry_id
    WHERE
        field_id_42 LIKE '" . mysqli_real_escape_string($event) . "';";

// Execute query
$query  = ee()->db->query( "$sql" );

It executes as expected, however I am seeing the following error in the error log:

Severity: Warning --> mysqli_real_escape_string() expects exactly 2 parameters, 1 given

What is the 'EE way' to pass the required connection parameters to the mysqli_real_escape_string() function?