ruby-on-rails - PG::错误:错误: ""处或附近的零长度定界标识符“”

Question

我只是转储了我的暂存数据库，然后在我的本地 postgres 数据库上做了 pg_restore 以使它们排队。所有数据都通过了。

现在，当我尝试在 Rails 控制台中查询时，出现错误。

Artist.count
   (0.5ms)  SELECT COUNT(*) FROM "artists" 
=> 668

**

Artist.last
  Artist Load (1.4ms)  SELECT "artists".* FROM "artists" ORDER BY "artists"."" DESC LIMIT 1
PG::Error: ERROR:  zero-length delimited identifier at or near """"
LINE 1: ...T  "artists".* FROM "artists"  ORDER BY "artists"."" DESC LI...
                                                             ^
: SELECT  "artists".* FROM "artists"  ORDER BY "artists"."" DESC LIMIT 1
ActiveRecord::StatementInvalid: PG::Error: ERROR:  zero-length delimited identifier at or near """"
LINE 1: ...T  "artists".* FROM "artists"  ORDER BY "artists"."" DESC LI...
                                                             ^
: SELECT  "artists".* FROM "artists"  ORDER BY "artists"."" DESC LIMIT 1
from /Users/ryanrebo/.rvm/gems/ruby-2.0.0-p481/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1161:in `exec'

我在所有其他模型上都遇到了同样的错误。我也不能使用 find(id)。

有什么想法吗？

Answer 1

错误发生是因为“artists”表没有用于排序的主键:

Artist Load (1.4ms) SELECT "artists".* FROM "artists" ORDER BY "artists"."" DESC LIMIT 1

通过将以下代码块添加到 Rails 迁移或在数据库中运行 alter table 命令来添加主键以修复:

execute <<-SQL ALTER TABLE assets ADD PRIMARY KEY (id); SQL

其中id是“artists”的主键。