SQL random sample with groups

Question

I have a university graduate database and would like to extract a random sample of data of around 1000 records.

I want to ensure the sample is representative of the pop

Answer 1

Add a table for storing population.

I think it should be like this:

SELECT *
FROM (
    SELECT id, coursecode, ROW_NUMBER() OVER (PARTITION BY coursecode ORDER BY NEWID()) AS rn
    FROM degree) t
    LEFT OUTER JOIN
    population p ON t.coursecode = p.coursecode
WHERE
    rn <= p.SampleSize