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SQL Query: 3 Methods for Calculating Cumulative SUM

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SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT t1.id, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON t1.id >= t2.id GROUP BY t1.id, t1.value ORDER BY t1.id; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than or

The tricky interview questions on IoT to read now

Internet of things is a tricky subject. I have given in this post on tricky interview questions asked for IoT Jobs. I have given simple to understand way. Mobile networks already deliver connectivity to a broad range of devices, enabling the development of innovative new services and applications. Why IoT you need This new wave of connectivity is going beyond tablets and laptops; to connected cars and buildings; TVs and game consoles; smart meters and traffic control; with the prospect of intelligently connecting almost anything and anyone. This is what the GSMA refers to as the “Connected Life”. As the Connected Life evolves, the number of mobile connections worldwide is set to rise dramatically to reach 10.5 billion by 2020, while the total number of connected devices across all access technologies could reach 25.6 billion1 . These devices will bridge the physical and digital worlds, enabling a new category of services that improve the quality of life and productivity of i