Changes between Version 6 and Version 7 of querries


Ignore:
Timestamp:
09/24/25 15:56:46 (13 days ago)
Author:
221046
Comment:

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  • querries

    v6 v7  
    3232||'''Фактури по корисник по датум'''||[[Image(invoice_per_customer_after_date.png, width=700)]]|| Враќа сите фактури за избраниот корисник; ако е зададен датум, ги филтрира по тој датум и пресметува вкупната сума. ||
    3333
    34 -- Релациона алгебра за прашалникот: Најпопуларен артист по жанр за корисник --
     34--Релациона алгебра за прашалникот: Најпопуларен артист по жанр за корисник--
    3535
    36 π g . genre_id, g . name → genre_name, ar . name → artist_name, COUNT (*) → play_count
    37   γ genre_id, name, name, COUNT (*)
    38    σ c . customer_id = 123
    39     (ρ c customer ⋈ c . customer_id = i . customer_id
    40      ρ i invoice ⋈ i . invoice_id = il . invoice_id
    41       ρ il invoice_line ⋈ il . track_id = tr . track_id
    42        ρ tr track ⋈ tr . genre_id = g . genre_id
    43         ρ g genre ⋈ tr . album_id = a . album_id
    44          ρ a album ⋈ a . artist_id = ar . artist_id
    45           ρ ar artist) in let maxplaycounts =
    46            π genre_id, MAX (play_count) → max_count
    47             γ genre_id, MAX (play_count) playcounts in
    48              π pc . genre_name, pc . artist_name, pc . play_count
    49               (ρ pc playcounts ⋈ pc . genre_id = mpc . genre_id AND pc . play_count = mpc . max_count
    50                ρ mpc maxplaycounts)
     36π g . genre_id, g . name → genre_name, ar . name → artist_name, COUNT (*) → play_count γ genre_id, name, name, COUNT (*) σ c . customer_id = 123 (ρ c customer ⋈ c . customer_id = i . customer_id ρ i invoice ⋈ i . invoice_id = il . invoice_id ρ il invoice_line ⋈ il . track_id = tr . track_id ρ tr track ⋈ tr . genre_id = g . genre_id ρ g genre ⋈ tr . album_id = a . album_id ρ a album ⋈ a . artist_id = ar . artist_id ρ ar artist) in let maxplaycounts = π genre_id, MAX (play_count) → max_count γ genre_id, MAX (play_count) playcounts in π pc . genre_name, pc . artist_name, pc . play_count(ρ pc playcounts ⋈ pc . genre_id = mpc . genre_id AND pc . play_count = mpc . max_count ρ mpc maxplaycounts)
    5137
    5238