Referring to a column alias in two tables

I have two hive SQL tables which consist of following columns.

table_1

|customer_id | ip_address|

region_table

|country_name | region_name|

I tried,

SELECT table_1.customer_id, table_1.ip_address, getCountry(ip_address) AS Country, region_table.region_name FROM table_1 JOIN region_table ON region_table.country_name = Country;

getCountry() is UDF which returns the country name when the IP address is passed into it. I want to use that country name to create another column with the corresponding region from the region_table. And i want to get the following table as my output.

customer_id | ip_address | Country | region_name

Any thoughts on what I'm missing in my query?

Solution

select      c.customer_id
           ,c.ip_address
           ,getCountry(c.ip_address) as Country
           ,r.region_name 

from                table_1         c

            join    region_table    r

            on      r.country_name = 
                    getCountry(c.ip_address)