Junior — Middle

Have you had experience using window functions in SQL queries?

sobes.tech AI

Answer from AI

Yes, window functions in SQL allow performing calculations across a set of table rows that are related to the current row, without grouping the data, which is useful for analytics and complex queries.

Example of using a window function for row numbering:

SELECT 
    user_id, 
    message, 
    ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY created_at DESC) AS rn
FROM messages
WHERE chat_id = 123;

In C# with Entity Framework or Dapper, such queries can be executed directly if the database supports window functions (e.g., PostgreSQL, SQL Server).

Window functions are useful for implementing pagination, calculating moving averages, ranking, and other tasks where context of the rows is needed.

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