Question

在我的数据库中，我有一堆列表，其中包含不同的城市名称。我试图只保留这个数据库中具有城市名称= X的列表，并删除所有其他城市。

我尝试以下活动记录查询：

@unwanted_cities = Listing.where('city not in (?)', Listing.where('city = ?', "X"));

但我得到了这个错误

ActiveRecord::StatementInvalid in Unwanted_cities#index

Showing /Users/AM/Documents/RailsWS/app0521/app/views/unwanted_cities/index.html.erb where     line #31 raised:

PG::Error: ERROR:  operator does not exist: character varying <> integer
LINE 1: SELECT "listings".* FROM "listings"  WHERE (city not in (4,1...
                                                     ^
HINT:  No operator matches the given name and argument type(s). You might need to add  explicit type casts.
: SELECT "listings".* FROM "listings"  WHERE (city not in         (4,10,13,17,18,19,21,23,26,28,29,31,36,39,46,48,49,52,90,97,101,103,105,108,109,111,115,94,5      ,219..............))

我做错了什么？

Answer 1

@unwanted_cities = Listing.where('city != ?', "X")

如果我正在阅读的内容是正确的，那么您希望城市没有名称＆＃34; X＆＃34;。您可以通过执行以上代码行来获得这些城市。

如果你想＆＃34;删除＆＃34;所有这些城市，

@unwanted_cities.delete_all

或

@unwanted_cities.destroy_all

如何使此活动记录查询工作

1 个答案: