what is the difference between group by and window function in sql

Question

Accepted Answer

Group by is used to group data based on a column while window function is used to perform calculations on a specific window of data.

Group by is used to aggregate data based on a specific column
Window function is used to perform calculations on a specific window of data
Group by is used with aggregate functions like sum, count, avg, etc.
Window function is used with analytical functions like rank, lead, lag, etc.
Group by creates a new table with aggregated data while window function does not
Example of group by: SELECT department, SUM(salary) FROM employees GROUP BY department
Example of window function: SELECT salary, AVG(salary) OVER (PARTITION BY department) FROM employees

Popular interview questions of Data Scientist