Inserting related data into two tables using in psql

Question

I am a newbie and have hit a road block trying to insert related values into two tables simultaneously. I would appreciate your guidance to solve this!

Table 1(players):

CREATE TABLE players(
  player_id serial PRIMARY KEY,
  player_name  varchar(50) NOT NULL);

Table 2(matches):

CREATE TABLE matches(
  player_id integer CONSTRAINT fk_links_match_player
  REFERENCES players(player_id) NOT NULL,
  match int NOT NULL,
  match_result varchar(4) NOT NULL
);

My function: I want the function to pass values to the query. I have tried multiple variations including the following but no luck so far.

def registerPlayer(name):
    cur.execute("""WITH player_key AS
               (INSERT INTO players(player_name) VALUES(%(name)s), {'name': name} RETURNING player_id)
               INSERT INTO matches (player_id, match, match_result) 
               VALUES((SELECT player_key.player_id), 1, 'won') """)

Answer 1

Do it in a single query:

query = """
    with player_key as (
        insert into players(player_name) 
        values (%(name)s) 
        returning player_id
    )
    insert into matches (player_id, match, match_result) 
    select player_id, 1, 'won'
    from player_key
"""

cursor.execute (query, {'name': name})

Answer 2

I'd do this way:

connection.begin()  # start a transaction
cur.execute("INSERT INTO players (player_name) VALUES (%(name)s) RETURNING player_id", {'name': name})
player_id = cur.fetchone()[0]
cur.execute("INSERT INTO matches (player_id, match, match_result) VALUES (%(player_id)s, 1, 'won')", {'player_id': player_id})
connection.commit()