Video: Dab tsi yog qhov tseem ceeb khaws cia lub rooj hauv Oracle nrog piv txwv?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
A tus yuam sij - khaws cia rooj yog lub hauv paus rooj nrog rau ib-rau-ib kab kev sib raug zoo nrog cov kab hauv kev pom, ntawm ob qho tib si thawj tus yuam sij los yog ib qho tshwj xeeb tus yuam sij . Hauv piv txwv saum toj no, cov tsheb rooj yog a tus yuam sij - khaws cia rooj.
Tsis tas li cov lus nug yog, dab tsi nrog kev xaiv kos hauv Oracle?
Oracle Nrog KUJ OPTION clause Lub WITH KUJ OPTION clause yog siv rau kev saib updataable los txwv tsis pub cov kev hloov pauv rau qhov pom uas yuav tsim cov kab uas tsis suav nrog hauv cov lus nug. Cov lus hauv qab no tsim ib qho kev pom uas muaj kab raws li qhov xwm txheej ntawm WHERE clause.
Tsis tas li ntawd, peb puas tuaj yeem tshem tawm ntawm kev saib hauv Oracle? Saib hauv Oracle tej zaum yuav hloov kho raws li tej yam kev mob tshwj xeeb. Nws ua tau ua kom yuam kev, thiab feem ntau tsis pom zoo. Ib qho updataable saib yog ib koj ua tau siv los ntxig, hloov kho, lossis rho tawm base rooj kab. Koj ua tau tsim ib saib yuav inherently updataable, los yog koj ua tau tsim ib qho INSTEM OF trigger rau ib qho twg saib kom nws updataable.
Tsis tas li ntawd, dab tsi yog updataable saib?
Ib updataable saib yog ib rooj plaub tshwj xeeb ntawm kev tshem tawm saib . Ib deletable saib ua ib updataable saib thaum tsawg kawg yog ib qho ntawm nws kab kho tau . Ib kem a saib yog kho tau thaum tag nrho cov cai hauv qab no muaj tseeb: Cov saib yog rho tawm.
Yuav ua li cas yog nrog check xaiv nyob rau hauv saib?
Nrog KUJ OPTION ntawm a saib . Nrog KUJ OPTION yog ib lub ntsiab lus xaiv ntawm CREATE SAIB nqe lus. Nws qhia txog qib ntawm kev tshuaj xyuas thaum cov ntaub ntawv raug tso lossis hloov kho los ntawm a saib . Yog nrog KUJ OPTION tau teev tseg, txhua kab uas tau ntxig lossis hloov kho los ntawm qhov saib yuav tsum ua raws li lub ntsiab txhais ntawm lub saib.
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