SQL Quick Revision + Practice Guide for Data Analyst/ Data Engineer Interviews — (Part — III)

Author(s): Kamireddy Mahendra

Originally published on Towards AI.

SQL Advanced Concept — Window Functions — In detailed and simple Guide

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To excel in data interviews, we must first revise all basic concepts in SQL, followed by mastering joins concepts. After that, prioritize understanding window functions in SQL, which are frequently asked and can significantly improve your chances of success.

I hope you already visited Part — I and Part — II of the SQL Quick Revision Series. If not I mentioned the article below.

SQL Concepts — Joins

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Window Functions are extensions of aggregate functions. Aggregate functions take multiple values as input and return only one value as output. Even if we consider table records, when we apply an aggregate function to any particular column in a table, we will get only a number as output. But, In window functions, we will get a number in each record.

Window Functions, or, as we call them, Analytical Functions, as these functions will give us privileges to return a value to each record without losing any data, and the value is related to the remaining records. So these window functions will be used for detailed data analysis or we can also consider them for row-wise data analysis.

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