mysql有全连接

SELECT *
FROM table1
LEFT JOIN table2 ON table1.id = table2.id
UNION
SELECT *
FROM table1
RIGHT JOIN table2 ON table1.id = table2.id;

SELECT COALESCE(table1.id, table2.id) AS id,
       table1.column1,
       table2.column2
FROM (SELECT id, column1 FROM table1
      UNION ALL
      SELECT id, NULL FROM table2
      WHERE id NOT IN (SELECT id FROM table1))
AS temp
JOIN table2 ON temp.id = table2.id
UNION ALL
SELECT COALESCE(table1.id, table2.id) AS id,
       table1.column1,
       table2.column2
FROM (SELECT id, NULL, column2 FROM table2
      UNION ALL
      SELECT id, column1, NULL FROM table1
      WHERE id NOT IN (SELECT id FROM table2))
AS temp
JOIN table1 ON temp.id = table1.id;