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 for ex。 start_age("20") 和 end_age("40")。

现在我想要年龄 (24 as integer) 介于 start_age 和 age_age 之间的用户。那么我怎样才能得到这个用户呢？

我试过这个查询

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

请写：

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)

这是一些演示 :

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)