Sql Postgres帮助的Oracle语法

我正在尝试从Oracle转换此代码：

CREATE VIEW PLANNED AS
SELECT ASP.ASP_SPACE_NM,
       SUM(MO.MO_TKR_TOTAL_OFF_SCHEDULED) "TOTAL_PLANNED"
  FROM OBJECTIVE MO, SPACE ASP
 WHERE ASP.ASP_SPACE_NM = MO.ASP_SPACE_NM (+)
   AND MO.MO_MSN_CLASS_NM = 'EPIC'
 GROUP BY ASP.ASP_SPACE_NM

去博士后

这其中有两行让我很困惑：

   SUM(MO.MO_TKR_TOTAL_OFF_SCHEDULED) "TOTAL_PLANNED"

这个和这个一样吗

   SUM(MO.MO_TKR_TOTAL_OFF_SCHEDULED) AS TOTAL_PLANNED

我不知道（+）在这行中是什么意思：

 WHERE ASP.ASP_SPACE_NM = MO.ASP_SPACE_NM (+)

---

这是老派的、特定于Oracle的左连接语法。您要将其替换为：

CREATE VIEW PLANNED AS
   SELECT s.asp_space_nm,
          SUM(o.mo_tkr_total_off_scheduled) 'total_planned'
     FROM SPACE s
LEFT JOIN OBJECTIVE o ON o.asp_space_nm = s.asp_space_nm 
                     AND o.mo_msn_class_nm = 'EPIC'
 GROUP BY s.asp_space_nm

参考：

---

该

+

表示（编辑：左）外部连接

及

确实很可能与

SUM(MO.MO_TKR_TOTAL_OFF_SCHEDULED) as "TOTAL_PLANNED"

如果我没记错的话，PostgreSQL中也不需要

as

（尽管在我看来这使它更加明确）

您可以查看Postgresql wiki上的以下页面以了解更多差异：

SUM(MO.MO_TKR_TOTAL_OFF_SCHEDULED) as "TOTAL_PLANNED"