Postgres 14

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create table players 
(
  id int generated always as identity primary key, 
  username text
);

insert into players  (username)
VALUES
  ('mike93'),
  ('james_op'),
  ('will_sniff')
;


CREATE TABLE



INSERT 0 3


ALTER TABLE players ADD COLUMN unique_id varchar(6) UNIQUE;

ALTER TABLE


create function generate_fake_id()
returns text
as
$$
  SELECT CONCAT('P', string_agg (substr('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789', ceil (random() * 62)::integer, 1), ''))
  FROM   generate_series(1, 5)
$$
language sql
volatile;

CREATE FUNCTION


update players
  set unique_id = generate_fake_id()
;

UPDATE 3


select *
from players
;


id
username
unique_id


1
mike93
PkqBjP

2
james_op
PZ58us

3
will_sniff
PaVx8H



SELECT 3