Postgres 16

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CREATE TABLE tablename (
    "id" int4 generated by default as identity NOT NULL);

CREATE TABLE

insert into tablename values(default),(default),(default) returning *;

id

1

2

3

INSERT 0 3

select pg_get_serial_sequence('tablename','id'),
       currval(pg_get_serial_sequence('tablename','id'));

pg_get_serial_sequence
currval

public.tablename_id_seq
3

SELECT 1

create sequence my_seq;
create table my_table(my_column int4 default nextval('my_seq') not null);
alter sequence my_seq owned by my_table.my_column;

CREATE SEQUENCE

CREATE TABLE

ALTER SEQUENCE

DO $r$
DECLARE my_table_name text:='my_table_'||(random()*1000)::int;
BEGIN
EXECUTE FORMAT ('CREATE TABLE %1$I ("id" serial NOT NULL);',my_table_name);
END $r$;

select tablename, 
       pg_get_serial_sequence(tablename,'id'),
       nextval(pg_get_serial_sequence(tablename,'id'))
from pg_tables where tablename ilike '%my_table_%';

DO

tablename
pg_get_serial_sequence
nextval

my_table_25
public.my_table_25_id_seq
1

SELECT 1