ruby-on-rails - 如何查找具有整数值而不是字符串的记录

Question

我有列字段作为字符串例如。 start_age("20") 和 end_age("40")。

现在我想要年龄(24 为整数)在 start_age 和age_age 之间的用户。那么我怎样才能获得这个用户呢？

我尝试过这个查询

User.where("start_age < (?) AND end_age > (?)", age, age)

但出现此错误:

PG::UndefinedFunction: ERROR:  operator does not exist: character varying < integer

提前致谢。

Answer 1

一定要写:

User.where("start_age::integer <= :age AND end_age::integer >= :age", age: age)
# or equivalent
User.where(":age BETWEEN start_age::integer AND end_age::integer", age: age)

这里有一些演示:

test_dev=# select 20  between '1'::integer and '10'::integer as result;
 result
--------
 f
(1 row)

test_dev=# select 5  between '1'::integer and '10'::integer as result;
 result
--------
 t
(1 row)

test_dev=# select '12'::integer as number;
 number
--------
     12
(1 row)