-- save the oauth user_id to keep track of all known users, and to link to accounts.

CREATE TABLE oauth_users (
	user_id		TEXT		NOT NULL,

	PRIMARY KEY (user_id)
);

INSERT INTO oauth_users (
	user_id
)
SELECT
	DISTINCT id_token_subject
FROM
	oauth_tokens;

ALTER TABLE oauth_tokens
	ADD CONSTRAINT fk_oauth_tokens_oauth_users
	FOREIGN KEY (id_token_subject)
	REFERENCES oauth_users (user_id);

ALTER TABLE accounts
	ADD COLUMN user_id TEXT
	UNIQUE
	REFERENCES oauth_users (user_id) NOT NULL;