Postgres 12

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CREATE TABLE tbl (
   tbl_id serial PRIMARY KEY
 , filename text
);

CREATE TABLE

INSERT INTO tbl(filename)
VALUES ('my_filename' || lastval())
RETURNING tbl_id;

tbl_id

1

INSERT 0 1

INSERT INTO tbl(filename)
VALUES ('my_filename' || currval('tbl_tbl_id_seq'))
RETURNING tbl_id;

tbl_id

2

INSERT 0 1

INSERT INTO tbl (filename)
VALUES ('my_filename' || currval(pg_get_serial_sequence('tbl', 'tbl_id')))
RETURNING tbl_id;

tbl_id

3

INSERT 0 1

SELECT * FROM tbl;

tbl_id
filename

1
my_filename1

2
my_filename2

3
my_filename3

SELECT 3