Merging two tables into one postrgesql?

Question

PostgreSQL

Conventionally, there are two tables:

create table target
(
  "id" serial primary key,
  "title" varchar(50) not null,
  "poster" varchar(100) default null
);

create table source
(
  "id" serial primary key,
  "posterId" serial REFERENCES target (id)
  "poster" varchar(100) default null
);

I need to copy source.poster to target.poster, according to the condition where source.posterId = target.id
I do this, the result is null

INSERT INTO target ("poster")
SELECT "poster"
FROM source
WHERE source."posterId" = target.id

Answer 1

Programmed in HTML, thanks for the tip to a friend who ran away somewhere

UPDATE target AS t
SET poster = s.poster 
FROM source AS s
WHERE s."posterId" = t.id