mysql - MySQLの完全な外部結合のヘルプをお願いします

Question

MySQLの完全外部結合が構文エラーであることは知っています。mysql5 に完全な外部結合があり、同様のクエリを作成したいと考えています。私は何をしますか？

Answer 1

You can emulate FULL OUTER JOIN using UNION (from MySQL 4.0.0 on):

with two tables t1, t2:

SELECT * FROM t1
LEFT JOIN t2 ON t1.id = t2.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id

with three tables t1, t2, t3:

SELECT * FROM t1
LEFT JOIN t2 ON t1.id = t2.id
LEFT JOIN t3 ON t2.id = t3.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id
LEFT JOIN t3 ON t2.id = t3.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id
RIGHT JOIN t3 ON t2.id = t3.id