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what is the intuition behind the window functions in sql? (programming.dev)

submitted 2 weeks ago by ghodawalaaman@programming.dev to c/programming@programming.dev

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I have been struggling to understand the window functions. I understand its use case like when you want to rank countries population per continent however the syntax is so weird it doesn't make any sense what actually happening

How does the sql server process this? does it run on every row? is there any benefit of using it over subquery?

sorry if this question is too dumb :(

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[–] Solemarc@lemmy.world 1 points 2 weeks ago

As far as SQL is concerned, all rows are the same. So a window function allows you to operate over multiple rows at once. So I say what I want it to do and how I want it to search e.g. "give me a single row per client_id where the session_date is max" will give me 1 row for each client with the client's newest session. This is the purpose of window functions.