Mysql实现Oracle的 full join

在Oracle中， 除了inner join，left join，right join，还有

full join

SELECT column_name(s) FROM table_name1 FULL JOIN table_name2 ON table_name1.column_name=table_name2.column_name

只要其中某个表存在匹配，FULL JOIN 关键字就会返回行

在Mysql中，是没有full join的，怎么去实现呢

左联 + 右联 + union

SELECT column_name(s) from table_name1 left join table_name2 on table_name1.column_name = table_name2.column_name 
union 
SELECT column_name(s) from table_name1 right join table_name2 on table_name1.column_name = table_name2.column_name