Windows and Frames
Learn about window functions and frames.
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There was SQL before window functions, and there is SQL after window functions: that’s how powerful this tool is!
The whole idea behind window functions is to allow us to process several values of the result set at a time: we see through the window some peer rows, and we’re able to compute a single output value from them, much like when using an aggregate function.
Windows and frames
PostgreSQL comes ...