| 336 | |
| 337 | π_{Genre, Period, PeriodType, LoanCount, MovingAverage} |
| 338 | (τ_{PeriodType ASC, Period DESC, LoanCount DESC} |
| 339 | (γ_{Genre, PeriodType, Period} |
| 340 | (σ_{Loan.LoanDate IS NOT NULL} |
| 341 | ( |
| 342 | (Book ⨝_{Book.BookID = Book_Copies.BookID} Book_Copies ⨝_{Book_Copies.CopyID = Loan.BookCopyID} Loan) |
| 343 | ) |
| 344 | ) |
| 345 | COUNT(*) → LoanCount |
| 346 | ) |
| 347 | ∪ |
| 348 | γ_{Genre, PeriodType, Period} |
| 349 | (σ_{Loan.LoanDate IS NOT NULL} |
| 350 | ( |
| 351 | (Book ⨝_{Book.BookID = Book_Copies.BookID} Book_Copies ⨝_{Book_Copies.CopyID = Loan.BookCopyID} Loan) |
| 352 | ) |
| 353 | ) |
| 354 | COUNT(*) → LoanCount |
| 355 | ) |
| 356 | ∪ |
| 357 | γ_{Genre, PeriodType, Period} |
| 358 | (σ_{Loan.LoanDate IS NOT NULL} |
| 359 | ( |
| 360 | (Book ⨝_{Book.BookID = Book_Copies.BookID} Book_Copies ⨝_{Book_Copies.CopyID = Loan.BookCopyID} Loan) |
| 361 | ) |
| 362 | ) |
| 363 | COUNT(*) → LoanCount |
| 364 | ) |
| 365 | ) |
| 366 | ⨝ |
| 367 | ( |
| 368 | γ_{Genre, PeriodType} |
| 369 | ( |
| 370 | WINDOW_{Genre, PeriodType, ORDER BY Period ROWS BETWEEN 2 PRECEDING AND CURRENT ROW} |
| 371 | ( |
| 372 | AVG(LoanCount) → MovingAverage |
| 373 | ) |
| 374 | ) |
| 375 | ) |
| 376 | |
| 377 | {{{#!sql |
| 378 | π (Genre, Period, PeriodType, LoanCount, MovingAverage) |
| 379 | | |
| 380 | τ (ORDER BY PeriodType, Period DESC, LoanCount DESC) |
| 381 | | |
| 382 | ⨝ (Join for Moving Average Calculation) |
| 383 | ┌────────────────────────────────────────┐ |
| 384 | | | |
| 385 | γ (GROUP BY Genre, PeriodType, Period, Aggregate Functions) γ (Moving Average Calculation) |
| 386 | | | |
| 387 | ∪ (UNION ALL) γ (OVER PARTITION Genre, PeriodType ORDER BY Period ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) |
| 388 | ┌──────────────────────────┴──────────────────────────┐ |
| 389 | | | | |
| 390 | γ (Monthly Loans) γ (Quarterly Loans) γ (Yearly Loans) |
| 391 | | | | |
| 392 | σ (LoanDate IS NOT NULL) σ (LoanDate IS NOT NULL) σ (LoanDate IS NOT NULL) |
| 393 | | | | |
| 394 | (Book ⨝ Book_Copies ⨝ Loan) (Book ⨝ Book_Copies ⨝ Loan) (Book ⨝ Book_Copies ⨝ Loan) |
| 395 | |
| 396 | }}} |