Cov txheej txheem:
Video: Kev saib puas tuaj yeem hloov kho?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Koj ua tau ntxig, hloov tshiab , thiab rho tawm kab hauv a saib , ua raws li cov kev txwv hauv qab no: Yog tias saib muaj koom nrog ntawm ntau lub rooj, koj ua tau tsuas ntxig thiab hloov tshiab ib lub rooj nyob rau hauv lub saib , thiab koj ua tau tsis rho tawm kab. Koj ua tau 'tsis ncaj qha hloov cov ntaub ntawv hauv kev pom raws li cov lus nug ntawm lub koomhaum.
Kuj tseem paub yog, thaum twg peb tuaj yeem hloov kho qhov pom?
kev prasad
- kev prasad. Teb Hnub Tim: Kaum Ib Hlis 31, 2007.
- Yog, peb tuaj yeem hloov kho saib, yog tias:-yog tias saib yog tsim rau ntawm ib lub rooj- yog tias saib muaj cov ntsiab lus tseem ceeb- yog tias saib muaj tag nrho cov tsis null teb ntawm cov lus hauv qab- yog tias saib cov lus nug tsis muaj pab pawg los ntawm lossis ib qho kev sib sau. teb.
Kuj Paub, peb tuaj yeem hloov kho qhov pom hauv Oracle? Teb: A SAIB hauv Oracle yog tsim los ntawm kev koom nrog ib los yog ntau lub rooj. Thaum koj hloov tshiab record(s) hauv a SAIB , nws tshiab cov ntaub ntawv nyob rau hauv cov lus hauv qab uas ua rau Saib . Yog li, yog, koj tuaj yeem hloov kho data hauv ib Oracle VIEW muab koj muaj cai tsim nyog rau lub hauv paus Oracle rooj.
Ib yam li ib tug yuav nug, puas SQL views hloov tshiab tau?
Hauv SQL ntawv Server tus qauv saib tsis muaj dab tsi tab sis cov lus nug. Raws li cov ntaub ntawv hauv qab hloov pauv, thaum cov lus nug ntawd nkag mus, nws cuam tshuam cov kev hloov pauv rau cov ntaub ntawv. Nws yog tsis siv neeg , tab sis tsis yog vim qee qhov kev txiav txim ntxiv tau tshwm sim rau refresh cov ntaub ntawv hauv kev pom.
Yog saib hloov tshiab thaum lub rooj hloov tshiab?
A saib yog ib qho kev nug khaws cia, nws tuav tsis muaj ntaub ntawv yog li tsis muaj, nws yuav tsis tau kho tshiab thaum lub rooj nws yog tsim rau yog. Tab sis sai li sai tau thaum koj siv cov saib cov lus nug nws yog raws li yuav khiav, yog li koj yuav saib cov kev hloov pauv tau ua rau lub hauv paus rooj . Yog, a saib yog SELECT query tiv thaiv hauv qab rooj / saib.
Pom zoo:
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