Cov txheej txheem:
Video: Peb puas tuaj yeem siv ob kab hauv kev faib los ntawm?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
PARTITION YOG ntau kab . Cov PARTITION YOG clause ua tau ua siv kom tawg tawm qhov rais nruab nrab ntawm ntau cov ntsiab lus ( kab ). Piv txwv li, koj ua tau xam cov hom phiaj nruab nrab ntawm lub caij nyoog thiab los ntawm lub teb chaws, lossis los ntawm lub xyoo daim ntawv qhia hnub (nrog rau hnub tim kem ).
Ib sab ntawm no, koj puas tuaj yeem muab faib los ntawm ob kab hauv SQL?
PARTITION LOS NTAWM ntau kab . Cov PARTITION YOG clause ua tau siv rau tawg tawm qhov rais nruab nrab ntawm ntau cov ntsiab lus ( kab ). Piv txwv li, koj ua tau xam cov hom phiaj nruab nrab ntawm lub caij nyoog thiab los ntawm lub teb chaws, lossis los ntawm lub xyoo daim ntawv qhia hnub (nrog rau hnub tim kem ).
Dab tsi yog muab faib los ntawm hauv SQL? Cov PARTITION BY clause yog subclause ntawm OVER clause. Cov PARTITION BY clause faib cov lus nug qhov tshwm sim rau hauv muab faib . Lub qhov rais muaj nuj nqi yog ua rau txhua tus muab faib cais thiab suav rov qab rau txhua tus muab faib.
Tom qab ntawd, ib tug kuj yuav nug, dab tsi yog sum over faib los ntawm?
SUM (Tag nrhoDue) Tshaj ( PARTITION LOS YOG CustomerID) AS 'Tag nrho Cov Neeg Muag Khoom' Qhov kev qhia no qhia SQL Server rau pawg ( muab faib ) cov ntaub ntawv los ntawm CustomerID thiab tsim cov neeg muag khoom tag nrho. Koj yuav pom tias tus nqi no zoo ib yam uas CustomerID rau kev txiav txim yog tib yam.
Koj nyob qib li cas hauv SQL?
SQL Server txhawb plaub lub luag haujlwm qeb duas:
- ROW_NUMBER: Muab tus lej txuas mus rau txhua kab hauv cov txiaj ntsig tau teeb tsa.
- RANK: Qeb txhua kab hauv cov txiaj ntsig tau teeb tsa.
- DENSE_RANK: Qeb txhua kab hauv cov txiaj ntsig tau teeb tsa.
- NTILE: Faib cov txiaj ntsig tau teeb tsa rau hauv tus lej ntawm pawg tau teev tseg raws li kev sib cav rau txoj haujlwm.
Pom zoo:
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