postgresql - Upsert 错误(On Conflict Do Update)指向重复的约束值

Question

当我尝试在 FROM 语句中使用多个源时，我在 Postgres 9.5 中遇到 ON CONFLICT DO UPDATE 问题。

工作代码示例:

    INSERT INTO new.bookmonographs  (citavi_id, abstract, createdon, edition, title, year)
SELECT "ID", "Abstract", "CreatedOn"::timestamp, "Edition", "Title", "Year"
FROM old."Reference"
WHERE old."Reference"."ReferenceType" = 'Book'
    AND old."Reference"."Year" IS NOT NULL
    AND old."Reference"."Title" IS NOT NULL
ON CONFLICT (citavi_id) DO UPDATE 
    SET (abstract, createdon, edition, title, year) = (excluded.abstract, excluded.createdon, excluded.edition, excluded.title, excluded.year)
; 

错误代码:

    INSERT INTO new.bookmonographs  (citavi_id, abstract, createdon, edition, title, year)
SELECT "ID", "Abstract", "CreatedOn"::timestamp, "Edition", "Title", "Year"
FROM old."Reference", old."ReferenceAuthor"
WHERE old."Reference"."ReferenceType" = 'Book'
    AND old."Reference"."Year" IS NOT NULL
    AND old."Reference"."Title" IS NOT NULL
    AND old."ReferenceAuthor"."ReferenceID" = old."Reference"."ID"
    --Year, Title and Author must be present in the data, otherwise the entry is deemed useless, hence won't be included
ON CONFLICT (citavi_id) DO UPDATE 
    SET (abstract, createdon, edition, title, year) = (excluded.abstract, excluded.createdon, excluded.edition, excluded.title, excluded.year)
; 

我在 FROM 语句和一个 WHERE 语句中添加了一个额外的源，以确保只有具有标题、年份和作者的条目被插入到新数据库中。 (如果旧的“Reference”，“ID”作为“ReferenceID”存在于旧的“ReferenceAuthor”中，那么作者就存在。)即使没有附加的 WHERE 语句，查询也是错误的。我在 SELECT 中指定的列仅出现在 old."Reference" 中，而不出现在 old."ReferenceAuthor" 中。 目前 old."ReferenceAuthor" 和 old."Reference" 没有 UNIQUE CONSTRAINT，专着的 uniqe 约束是:

CONSTRAINT bookmonographs_pk PRIMARY KEY (bookmonographsid),
CONSTRAINT bookmonographs_bookseries FOREIGN KEY (bookseriesid)
      REFERENCES new.bookseries (bookseriesid) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT bookmonographs_citaviid_unique UNIQUE (citavi_id)

PSQL 抛出的错误:

ERROR: ON CONFLICT DO UPDATE command cannot affect row a second time HINT: Ensure that no rows proposed for insertion within the same command have duplicate constrained values. ********** Error **********

ERROR: ON CONFLICT DO UPDATE command cannot affect row a second time SQL state: 21000 Hint: Ensure that no rows proposed for insertion within the same command have duplicate constrained values.

我不知道出了什么问题，或者为什么提示指向重复的约束值。

Answer 1

问题是由于某些条目显然有多个作者这一事实引起的。因此，您编写的选择查询中的内部联接将为同一条目返回多行，而 INSERT ... ON CONFLICT 不喜欢这样。由于您仅使用 ReferenceAuthor 表进行过滤，因此您可以简单地重写查询，以便它使用该表通过执行 exists 来仅过滤没有任何作者的条目> 在相关子查询上。方法如下:

INSERT INTO new.bookmonographs  (citavi_id, abstract, createdon, edition, title, year)
SELECT "ID", "Abstract", "CreatedOn"::timestamp, "Edition", "Title", "Year"
FROM old."Reference"
WHERE old."Reference"."ReferenceType" = 'Book'
    AND old."Reference"."Year" IS NOT NULL
    AND old."Reference"."Title" IS NOT NULL
    AND exists(SELECT FROM old."ReferenceAuthor" WHERE old."ReferenceAuthor"."ReferenceID" = old."Reference"."ID")
    --Year, Title and Author must be present in the data, otherwise the entry is deemed useless, hence won't be included
ON CONFLICT (citavi_id) DO UPDATE 
    SET (abstract, createdon, edition, title, year) = (excluded.abstract, excluded.createdon, excluded.edition, excluded.title, excluded.year)
;