HANA 2.0 SPS05中如何正确使用LEFT LATERAL JOIN？

基础信息 #

• 环境：SAP Business One | HANA 版本：2.0 SPS05
• 需求：查询所有供应商及其最后一张采购订单的订单编号（DocNum）和订单日期（DocDate）

问题说明 #

使用CTE结合窗口函数可正常实现该查询，但尝试通过LEFT LATERAL JOIN实现时，会触发错误：incorrect syntax near "WHERE"。根据相关评论，LATERAL JOIN特性的文档在HANA 2.0 SPS05版本后不再提供，推测该版本的该功能存在兼容性问题。

可行实现方案（CTE+窗口函数） #

WITH Last_PO AS (
 SELECT 
  "CardCode", "DocNum", "DocDate"
  ,ROW_NUMBER() OVER (PARTITION BY "CardCode" ORDER BY "DocEntry" DESC) row_num
 FROM OPOR
 WHERE "CANCELED" = 'N'
)

SELECT
 OCRD."CardCode"
 ,OCRD."CardName"
 ,Last_PO."DocNum" AS "Last PO"
 ,Last_PO."DocDate" AS "Last PO Date"
FROM
 OCRD LEFT JOIN Last_PO on Last_PO.row_num = 1 AND Last_PO."CardCode" = OCRD."CardCode"
WHERE
 OCRD."CardType" = 'S'
ORDER BY
 OCRD."CardCode"

报错的LEFT LATERAL JOIN实现方案 #

SELECT
 OCRD."CardCode"
 ,OCRD."CardName"
 ,Last_PO."DocNum" AS "Last PO"
 ,Last_PO."DocDate" AS "Last PO Date"
FROM
 OCRD LEFT JOIN LATERAL (
  SELECT "DocNum", "DocDate"
  FROM OPOR 
  WHERE "CANCELED" = 'N' AND "CardCode" = OCRD."CardCode"
  ORDER BY "DocEntry" DESC
  LIMIT 1
) Last_PO ON TRUE
WHERE
 OCRD."CardType" = 'S'
ORDER BY
 OCRD."CardCode"

内容的提问来源于stack exchange，提问作者Bangaio