错误：零长度定界标识符位于“”或“附近”。第1行：从“区域”中删除在“区域”中。 = $ 1 [英] ERROR: zero-length delimited identifier at or near """" LINE 1: DELETE FROM "regions" WHERE "regions"."" = $1

问题描述

我将Rails 4.1和Postgresql（带有PG gem）用作数据库。从公司到省份，我有很多对很多的协会，有一个名为region的联接表。现在很明显regions表没有主键，因为我使用了{：id => false}。但是，当我尝试使用dependency destroy或仅对自身的区域对象调用destroy时，我会收到此错误：

I'm using Rails 4.1 and Postgresql (with PG gem) as my database. I have a very stand many to many association from companies to provinces with a join table called regions. Now obviously the regions table has no primary key cause I used { :id => false }. But when I try to use depending destroy or just simply calling destroy on the region object it self I get this error:

 ERROR:  zero-length delimited identifier at or near """"
 LINE 1: DELETE FROM "regions" WHERE "regions"."" = $1

我知道问题是由于缺少Regions表的主键引起的。奇怪的是，如果我将主键添加回表中，destroy可以正常工作并且没有错误。但是，如果我从表中删除主键，则会返回错误。我知道这与postgres有关，但是我不知道如何解决这个问题而不必在我的regions表中添加主键列。

I know the problem is caused due to the lack of a primary key for the regions table. And oddly if I add the primary key back to the table destroy works fine and no error. However, if I remove the primary key from the table the error comes back. I know this has something to do with the postgres but I've no idea how to solve this without having to add a primary key column to my regions table.

这里是实际查询

[DEBUG] [AdminUser Load (0.4ms)  SELECT  "admin_users".* FROM "admin_users"  WHERE "admin_users"."id" = 1  ORDER BY "admin_users"."id" ASC LIMIT 1] (pid:29655)
[DEBUG] [Province Load (0.2ms)  SELECT  "provinces".* FROM "provinces"  WHERE "provinces"."id" = $1 LIMIT 1  [["id", 5]]] (pid:29655)
[DEBUG] [ (0.1ms)  BEGIN] (pid:29655)
[DEBUG] [Region Load (0.3ms)  SELECT "regions".* FROM "regions"  WHERE "regions"."province_id" = $1  [["province_id", 5]]] (pid:29655)
[ERROR] [PG::SyntaxError: ERROR:  zero-length delimited identifier at or near """"
LINE 1: DELETE FROM "regions" WHERE "regions"."" = $1

推荐答案

您希望单引号不要在空字符串周围加上双引号，双引号必须定界标识符，而不是有意义的标识符。

You want single quotes not double quotes around empty strings, double quotes make delimited identifiers, and "" isn't a meaningful identifier.

尝试：

WHERE 'regions'.'' = $1

或至少：

WHERE "regions".'' = $1

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