Does TDSQL for MySQL support window functions?

Yes, TDSQL for MySQL supports window functions. Window functions allow for calculations across sets of rows related to the current row, which can be useful for tasks such as ranking, percentiles, and moving averages without collapsing the result set.

For example, consider a scenario where you have a table named sales with columns id, product, quantity, and sale_date. If you want to calculate the cumulative sales quantity for each product up to a certain date, you could use a window function like this:

SELECT 
    product,
    sale_date,
    quantity,
    SUM(quantity) OVER (PARTITION BY product ORDER BY sale_date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS cumulative_quantity
FROM 
    sales
ORDER BY 
    product, sale_date;

In this query, SUM(quantity) OVER (...) is the window function that calculates the cumulative sum of quantities for each product, ordered by sale_date. The PARTITION BY clause divides the result set into partitions to which the function is applied independently, and ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW defines the range of rows within the partition to include in the calculation.

Tencent Cloud's TDSQL for MySQL, being a managed database service, leverages the capabilities of MySQL 8.0 and later versions, which include support for window functions. This allows users to take advantage of advanced SQL features without managing the underlying infrastructure.