Obtener los valores de un enum. From http://stackoverflow.com/questions/2350052/how-can-i-get-enum-possible-values-in-a-mysql-database

get_enum_values.php

function get_enum_values( $table, $field )
{
    $type = $this->db->query( "SHOW COLUMNS FROM {$table} WHERE Field = '{$field}'" )->row( 0 )->Type;
    preg_match("/^enum\(\'(.*)\'\)$/", $type, $matches);
    $enum = explode("','", $matches[1]);
    return $enum;
}