Oracle-->Postgres查询

我是一个Oracle的家伙，试图将这样的查询转换为Postgres。没有真正理解所有的语法等，希望有人能帮助

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

您可以尝试使用外部联接

您似乎不需要使用子查询，因为您没有在子查询中执行任何操作，只选择原始列。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

IIRC+是一个左连接

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