Postgresql :Flet 2 lignende databaser

Først skal du indlæse tabellerne i to separate skemaer i den samme database.

CREATE SCHEMA db1;
CREATE TABLE db1.table1 (id INT PRIMARY KEY, value VARCHAR(10));
-- load the contents of Table1 @ Database1 into db1.table1

CREATE SCHEMA db2;
CREATE TABLE db2.table1 (id INT PRIMARY KEY, value VARCHAR(10));
-- load the contents of Table1 @ Database2 into db2.table1

Derefter kan du slå de to sammen ved at prioritere db2 over db1.

SELECT
  DISTINCT ON (id)
  id,
  value
FROM (
  SELECT
    *,
    1 AS db
  FROM
    db1.table1

  UNION

  SELECT
    *,
    2 AS db
  FROM
    db2.table1) AS mix
ORDER BY
  id,
  db DESC;