本文介绍了如何在Oracle中使用RIGHT JOIN, LEFT JOIN和INNER JOIN进行兼容查询，并指出MySQL不支持FULL JOIN的情况。重点讲解了在两种数据库系统之间的转换方法。
MySQL和Oracle兼容写法
方法:
SELECT * FROM (SELECT 1 AS a,2 AS b,3 AS c FROM dual) t1 RIGHT JOIN (SELECT 4 AS d,5 AS e FROM dual) t2 ON 1=1
或
SELECT * FROM (SELECT 1 AS a,2 AS b,3 AS c FROM dual) t1 LEFT JOIN (SELECT 4 AS d,5 AS e FROM dual) t2 ON 1=1
或
SELECT * FROM (SELECT 1 as a,2 as b,3 as c FROM dual) t1 INNER JOIN (SELECT 4 AS d,5 AS e FROM dual) t2 ON 1=1
结果:
注: 以下方法适用于Oracle, 不适用于MySQL
因为MySQL不支持FULL JOIN 写法
SELECT * FROM (SELECT 1 AS a,2 AS b,3 AS c FROM dual) t1 FULL JOIN (SELECT 4 AS d,5 AS e FROM dual) t2 ON 1=1
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