How to use RANK() Function In SQL
The RANK() function assigns a rank to each row within a partition, allowing for the selection of top N rows per group based on ranking.
Query:
SELECT *
FROM (
SELECT *,
RANK() OVER (PARTITION BY region ORDER BY sales_amount DESC) AS rank_num is calculated.
FROM sales_data
)
WHERE rank_num <= 2;
Output:
Explanation: The output presents records from the sales_data table where each row is assigned a rank based on the sales amount within its region, sorted in descending order. Only rows with ranks less than or equal to 2 are displayed.
How to Restrict Results to top N Rows per Group in PL/SQL?
In the world of database administration, retrieving top N rows from every grouping is a frequent but complicated one. Whether you are performing cross-tabulations with large datasets or looking for specific insights within the grouping of data, the ability to restrict the output to top N rows per group is precious.
Implementing this job in PL/SQL, which is Oracle’s procedural extension to SQL, may call for a thought-out approach applying approaches customized for the database environment. Now is the time to explore a how-to and a methodology for determining top N results per group in PL/SQL.