Question #170

CREATE TABLE some_table (
  col1 integer,
  col2 integer,
  UNIQUE (col1, col2)
);

INSERT INTO some_table (col1, col2) VALUES
  (1, 1),
  (2, 1),
  (1, 2),
  (1, NULL),
  (1, NULL),
  (NULL, 1),
  (NULL, 1),
  (NULL, NULL),
  (NULL, NULL)
ON CONFLICT DO NOTHING;