Escapes a field name string.
Force all field names to be strictly alphanumeric-plus-underscore. For some database drivers, it may also wrap the field name in database-specific escape characters.
string The sanitized field name string.
public function escapeField($field) {
if (!isset($this->escapedNames[$field])) {
$this->escapedNames[$field] = preg_replace('/[^A-Za-z0-9_.]+/', '', $field);
}
return $this->escapedNames[$field];
}