Postgres 14

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create table test (id int, firstname varchar(128), lastname varchar(128));

CREATE TABLE


insert into test values(1,'albert','einsten');
insert into test values(2,'isaac','newton');
insert into test values(3,null, 'curie');
insert into test values(4,'alexandre','Graham Bell');
insert into test values(5,'thomas','Edison');

INSERT 0 1



INSERT 0 1



INSERT 0 1



INSERT 0 1



INSERT 0 1


SELECT *
FROM test
ORDER BY id


id
firstname
lastname


1
albert
einsten

2
isaac
newton

3
null
curie

4
alexandre
Graham Bell

5
thomas
Edison



SELECT 5


update test
SET firstname = t2.firstname
FROM
(
 SELECT id, COALESCE(LAG(firstname, 1) OVER (ORDER BY id RANGE UNBOUNDED PRECEDING), LAST_VALUE(firstname) OVER (ORDER BY id RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)) firstname
 FROM test t2
 WHERE firstname IS NOT NULL
) t2
WHERE test.id = t2.id

UPDATE 4


SELECT *
FROM test
ORDER BY id


id
firstname
lastname


1
thomas
einsten

2
albert
newton

3
null
curie

4
isaac
Graham Bell

5
alexandre
Edison



SELECT 5

id	firstname	lastname
1	albert	einsten
2	isaac	newton
3	null	curie
4	alexandre	Graham Bell
5	thomas	Edison