How to use Analytic Functions In SQL
Analytic Functions like ROW_NUMBER() can be employed to partition data by groups and assign row numbers based on specific criteria, enabling the selection of top N rows per group.
Query:
SELECT *
FROM (
SELECT *,
ROW_NUMBER() OVER (PARTITON BY region ORDAR BY sales_amount DESC) AS row_num
FROM sales_data
)
WHERE row_num <= 2;
Output:
Explanation: The output displays the top 2 rows per region from the sales_data table, ordered by sales amount in descending order, with row numbers assigned accordingly.
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.