OAuth2 client_secret列不允许为null

Question

Why is in this OAuth database scheme from Brent Shaffer the client_secret column not allowed to be null (client_secret VARCHAR(80) NOT NULL)? Is this the common configuration for a valid OAuth database schema?

The OAuth2-Server Module can also be found on GitHub but also in the PDO scheme there the client_secret column is set NOT NULL.

CREATE TABLE oauth_clients (
  client_id VARCHAR(80) NOT NULL, 
  client_secret VARCHAR(80) NOT NULL, 
  redirect_uri VARCHAR(2000) NOT NULL, 
  grant_types VARCHAR(80), 
  scope VARCHAR(100), 
  user_id VARCHAR(80), 
  CONSTRAINT clients_client_id_pk PRIMARY KEY (client_id)
);

It is quite common to have public clients that don't need a password. I see that people set an empty string('') in such cases, but a null values seems much cleaner to me.

Is there some special reason to prohibit null values in this case?

Answer 1

I got an answer on GitHub: "NULL is fine for client_secret".