How to Efficiently Retrieve the Latest Position for Each Security Using SQL?

Groupwise Maximum: Retrieving Latest Position for Each Security

In the provided dataset, you aim to retrieve the latest position for each security. You have attempted using a query based on the MAX() aggregate function, but it only returns a single row.

To address this, you can employ an alternative approach that utilizes LEFT JOIN. Below is an optimized query that efficiently achieves the required result:

SELECT p1.id,
       p1.security,
       p1.buy_date
       FROM positions p1
left join
            positions p2
                on p1.security = p2.security
                   and p1.buy_date < p2.buy_date
      where
      p2.id is null;

This query performs an outer join of the table with itself, excluding rows where a later buy date exists for the same security. Consequently, it returns a single row for each security with the latest buy date.

By utilizing this optimized approach, you can significantly reduce the query execution time and retrieve the desired information efficiently.

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