SQL Function Get Column By Reference - sql

Question

Let's say there are 3 tables: Genders, Countries and Users. Users has among others a column named Gender and also a column named Country.
I want to add a new entry to Users and select one of the columns Male/Female {M, F} and a country from the rows of Countries dynamically just for testing purposes.
insert into dbo.[Users] (Gender, UserName, Country)
select Genders.Male, 'newbie', Countries.(the one which matches column CountryId) FROM Genders, Countries
I want to achieve this: 'M', 'newbie', MyCountry
After applying the suggestion from 'zip' I get the result 2 rows affected, same number as the external tables I'm referencing. The Query added 2 rows, so I guess I am missing the WHERE conditions.
The Genders Table is meant as a Property and will have only one row that I manually added.
Table Genders; 1 row
Male : uniqueidentifier
Female : uniqueidentifier
Countries is a table with many rows, so I want to select one matching the criteria of one of it's column values, say the value of column CountryId.

Answer 1

You can get a random value using:
insert into dbo.[Users] (Gender, UserName)
select top (1) g.Male, 'newbie'
from Genders.Male
order by newid();

Answer 2

I figuored the solution out. Thank you all who responded for pointing me in the right direction.
INSERT INTO dbo.[Users] (Gender, UserName, Country)
SELECT Genders.Male, 'newbie', Countries.CountryId
FROM Genders, Countries
WHERE Countries.ISO2 = '##'
'##' = 2 letter ISO of country.
Explanation:
1. INSERT INTO dbo.[Users] = Add a new row to Table "Users"
2. (Gender, UserName, Country) = Includes the columns in table "Users". If a column is not specified and it had a property of not allowing Nulls, an exception would be thrown!
3. FROM Genders, Countries = Include the external tables associated to look for
4. WHERE Countries.ISO2 = '##' = This condition allows you to precisely select which column of which row you seek. So I searched for a certain row where a column named ISO2 had a value '##' and looked then for the CountryId value in the same row (entry). There may be cases when multiple rows have identical value so you would have to further specify the conditions by using AND or OR oeprators.
When a table does not contain more than 1 row, I should not have to apply WHERE Conditions. It will select the default one existing. But because the Countries Table had multiple items (3 Rows), leaving the WHERE clause out, caused to add 3 times the same User, with each row having a distinct CountryId!