How to Restrict Results to Top N Rows per Group in MySQL
When dealing with databases, limiting results to the top N rows within specific groups is crucial. We’ll explore three approaches in MySQL to efficiently handle this scenario.
- Using Subquery with
ROW_NUMBER() - Using Common Table Expression (CTE)
- Using
DENSE_RANK()for Tie-Breaking
Syntax:
SELECT *
FROM (
SELECT
your_columns,
ROW_NUMBER() OVER (PARTITION BY your_grouping_column ORDER BY your_ordering_column DESC) AS row_num
FROM
your_table
) ranked
WHERE
row_num <= N;
How to Restrict Results to Top N Rows per Group in MySQL
When working with MySQL databases, the need to limit results to the top N rows per group is a common requirement. This is particularly useful in scenarios where you aim to retrieve a specific number of records for each distinct group in your dataset. Achieving this involves leveraging the ROW_NUMBER() window function along with the PARTITION BY clause to effectively partition the data into groups.
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