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我正在将旧的 oracle sql join 语法转换为 postgres 中兼容的 ANSI sql 代码。我正在使用 python 来为此目的创建实用程序。到目前为止，我的研究非常好，我发现使用sqlparserpython 库。

示例 sql 语法：

  SELECT i.product_id
,      d.language_id
,      CASE WHEN d.language_id IS NOT NULL
            THEN d.translated_name
            ELSE TRANSLATE(i.product_name USING NCHAR_CS)
       END    AS product_name
,      i.category_id
,      CASE WHEN d.language_id IS NOT NULL
            THEN d.translated_description
            ELSE TRANSLATE(i.product_description USING NCHAR_CS)
       END    AS product_description
,      i.weight_class
,      i.warranty_period
,      i.supplier_id
,      i.product_status
,      i.list_price
,      i.min_price
,      i.catalog_url
FROM   product_information  i
,      product_descriptions d
WHERE  d.product_id  (+) = i.product_id
AND    d.language_id (+) = sys_context('USERENV','LANG');

预期输出：

  SELECT i.product_id
,      d.language_id
,      CASE WHEN d.language_id IS NOT NULL
            THEN d.translated_name
            ELSE TRANSLATE(i.product_name USING NCHAR_CS)
       END    AS product_name
,      i.category_id
,      CASE WHEN d.language_id IS NOT NULL
            THEN d.translated_description
            ELSE TRANSLATE(i.product_description USING NCHAR_CS)
       END    AS product_description
,      i.weight_class
,      i.warranty_period
,      i.supplier_id
,      i.product_status
,      i.list_price
,      i.min_price
,      i.catalog_url
FROM   product_information  i right outer join product_descriptions d

on 
d.product_id   = i.product_id 
and    d.language_id = sys_context('USERENV','LANG');

到目前为止，我已经尝试过这样的。我有标记，但不确定如何在旧版 Oracle 连接语法的情况下交换位置。如果有人可以提供一些见解。我对 python 很陌生。

import sqlparse

query= '''
    SELECT i.product_id
,      d.language_id
,      CASE WHEN d.language_id IS NOT NULL
            THEN d.translated_name
            ELSE TRANSLATE(i.product_name USING NCHAR_CS)
       END    AS product_name
,      i.category_id
,      CASE WHEN d.language_id IS NOT NULL
            THEN d.translated_description
            ELSE TRANSLATE(i.product_description USING NCHAR_CS)
       END    AS product_description
,      i.weight_class
,      i.warranty_period
,      i.supplier_id
,      i.product_status
,      i.list_price
,      i.min_price
,      i.catalog_url
FROM   product_information  i
,      product_descriptions d
WHERE  d.product_id  (+) = i.product_id
AND    d.language_id (+) = sys_context('USERENV','LANG')'''


res=sqlparse.parse(query)
stmt = res[0]
print (stmt.tokens[-1])

输出我得到 where 子句连接

WHERE  d.product_id  (+) = i.product_id
AND    d.language_id (+) = sys_context('USERENV','LANG');

我被困在这里，如何将其重写为

FROM   product_information  i right outer join product_descriptions d    
on  d.product_id   = i.product_id 
and    d.language_id = sys_context('USERENV','LANG');
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