Postgres 15

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CREATE TABLE load_record (
  id int PRIMARY KEY,
  document_number int NOT NULL,
  document_status text NOT NULL CHECK (document_status IN ('INFORMED', 'APPROVED', 'EDITED', 'RESULTANT')),
  is_unique bool NOT NULL DEFAULT TRUE,
  parent_load_record_id int REFERENCES load_record
);

INSERT INTO load_record(id, document_number, document_status, parent_load_record_id) VALUES
  (276983, 49515, 'INFORMED', NULL),
  (1060396, 251013, 'INFORMED', NULL),
  (177836, 0000221, 'INFORMED', NULL),
  (207775, 0000221, 'APPROVED', 177836),
  (19342, 0000221, 'RESULTANT', 177836),
  (19721, 000456, 'INFORMED', NULL),
  (19786, 000456, 'EDITED', 19721);

CREATE TABLE

INSERT 0 7

SELECT DISTINCT parent_load_record_id FROM load_record;

parent_load_record_id

null

177836

19721

SELECT 3

SELECT 
  l.id,
  l.id NOT IN(SELECT DISTINCT parent_load_record_id FROM load_record)
FROM load_record l
WHERE l.parent_load_record_id IS NULL;

id
?column?

276983
null

1060396
null

177836
f

19721
f

SELECT 4