Oracle-> Postgres查询

Question

我是一个Oracle家伙，试图将这样的查询转换为Postgres。不太了解所有语法，等等。希望有人可以提供帮助吗？

Oracle查询：     

    SELECT c.code, c.recommendation, s.suggested, s.sugg_by, a.approved, a.app_by
    FROM (SELECT code, recommendation FROM recommendations) c,
         (SELECT code, suggested, sugg_by FROM suggestions) s,
         (SELECT code, approved, app_by FROM suggestions) a
    WHERE c.code = s.code(+)
      AND c.code = a.code(+);
    

非常感谢

Answer 1

您可以尝试使用OUTER JOIN

SELECT c.code, c.recommendation, s.suggested, s.sugg_by, a.approved, a.app_by
FROM (SELECT code, recommendation FROM recommendations) c 
LEFT JOIN (SELECT code, suggested, sugg_by FROM suggestions) s on c.code = s.code
LEFT JOIN (SELECT code, approved, app_by FROM suggestions) a ON c.code = a.code

您似乎不需要使用子查询，因为您在子查询中没有执行任何操作，仅选择了原始列。您可以直接查询该表。

SELECT
    c.code,
    c.recommendation, 
    s.suggested,
    s.sugg_by, 
    a.approved,
    a.app_by
FROM recommendations c 
LEFT JOIN suggestions s on c.code = s.code
LEFT JOIN suggestions a ON c.code = a.code