How can I perform stratified sampling in SQL with a specified sample size?

Sophia39 · January 28, 2025, 3:38pm

I have a dataset consisting of the following values:
 x y y z z z z 
I’m looking for a SQL query that will produce a stratified sample of a chosen size. For instance, if I want a sample size of 4, I would anticipate the result to look like this:
 x y z z 

ZoeString42 · February 1, 2025, 5:07am

hey Sophia! You can use the TABLESAMPLE feature, but not all SQL databases support it. If you’re using PostgreSQL, you may need to use a CASE or ROW_NUMBER along with a common table expression (CTE) or subquery to get stratifed sampling. This way, you keep the proportions intact as you select.