独特contraint违反更新的声明

我有以下查询：独特contraint违反更新的声明

UPDATE "PostsTags" 
SET "TagId" = "PostsTags"."TagId" #tgs."mainId" 
FROM (
    SELECT t1."TagId" AS "mainId", t1.text AS "mainText", t2."TagId" AS "malformedId", t2.text AS "malformedText" 
    FROM "TagTranslations" t1 
    INNER JOIN "TagTranslations" t2 ON t1.text = regexp_replace(t2.text, '^\s+','') AND t2.id != t1.id 
    WHERE regexp_replace(t1.text, '^\s+','') = t1.text AND t1."language" = 'en-us' 
) tgs 
WHERE "PostsTags"."TagId" = tgs."malformedId" AND "PostsTags"."language" = 'en-us' AND "PostsTags"."PostId" = 281 
RETURNING *

正如你可以看到我更新TagId = TagId（我设置相同的值，标签识别列）。我得到以下错误：

ERROR: duplicate key value violates unique constraint "PostsTags_pkey" 
DETAIL: Key (language, "PostId", "TagId")=(en-us, 281, 10157) already exists.

有人可以告诉我如何可能我收到这种违规行为，而我实际上没有改变任何东西吗？

来源

2014-09-20 user606521

那是什么位“#tgs ......”在干什么？ 'SET'TagId“=”TagId“#tgs。”mainId“' – 2014-09-20 16:03:32

您正在使用子查询中的值更新'TagId'。所以这肯定会造成重复。 – Wolph 2014-09-20 18:22:40

'#tgs。“mainId”'只是评论。我只是将TagId设置为其以前的值，以便如何导致违规？ – user606521 2014-09-20 22:25:55

#不会引入评论。它是按位XOR运算符。 The manual

有关行的末尾为此评论，请使用-- THIS Is a Comment

UPDATE "PostsTags" 
SET "TagId" = "PostsTags"."TagId" -- COMMENTED OUT: tgs."mainId" 
FROM (
    SELECT t1."TagId" AS "mainId", t1.text AS "mainText", t2."TagId" AS "malformedId", t2.text AS "malformedText" 
    FROM "TagTranslations" t1 
    INNER JOIN "TagTranslations" t2 ON t1.text = regexp_replace(t2.text, '^\s+','') AND t2.id != t1.id 
    WHERE regexp_replace(t1.text, '^\s+','') = t1.text AND t1."language" = 'en-us' 
) tgs 
WHERE "PostsTags"."TagId" = tgs."malformedId" AND "PostsTags"."language" = 'en-us' AND "PostsTags"."PostId" = 281 
-- RETURNING * 
    ;

BTW：还有不保证更新是正确的;子查询可能结果在多个匹配元组返回一个给定t2.TagId - >tgs."malformedId" - >"postTags"."TagId"

来源

2014-09-22 12:58:06 joop

独特contraint违反更新的声明

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