PK thiab Clustered yuam sij yog cov ntsiab lus sib cais. Koj PK tsis tas yuavua koj qhov ntsuas ntsuas qhov tseem ceeb. Hauv kev siv tswv yim hauv kuv tus kheej qhov kev paub dhau los, tib thaj chaw uas yog koj li PK yuav tsum / yuav yog koj qhov tseem ceeb ntawm pawg vim nws ua tau raws li cov qauv sau saum toj no.
Yuav tsum muab tus yuam sij tseem ceeb ua pawg?
Primary Key tuaj yeem ua Clustered lossis Tsis yog pawg tab sis nws yog ib qho kev coj ua zoo tshaj plaws los tsim Cov Ntsiab Cai Tseem Ceeb raws li Cov Ntawv Qhia Ua Pawg. … Lub Ntsiab Tseem Ceeb yuav tsum yog cim qhia kab ntawm lub roojthiab nws yuav tsum TSIS NULL.
PK pawg yog dab tsi?
Clustered Index. Ib pawg ntsuas txhais qhov kev txiav txim uas cov ntaub ntawv khaws cia hauv lub cev hauv lub roojCov ntaub ntawv cov lus tuaj yeem txheeb xyuas tib txoj kev, yog li ntawd, tsuas muaj ib qho kev ntsuas ntawm ib lub rooj xwb. Hauv SQL neeg rau zaub mov, thawj qhov tseem ceeb txwv cia li tsim ib pawg indexed ntawm kab ntawv tshwj xeeb.
Puas yog tus yuam sij tseem ceeb tsis yog pawg?
Ib tus yuam sij tseem ceeb yog zais qhov ntsuas! Nws tuaj yeem ua pawg lossis tsis suav nrog. Koj tus yuam sij tseem ceeb yuav yog "tus yuam sij hloov pauv ".
Dab tsi yog qhov txiaj ntsig ntawm pawg ntsuas ntsuas?
Ib pawg ntsuas ntsuas yog siv tau rau ntau cov lus nug vim tias cov ntaub ntawv raug txheeb xyuas ntawm tus yuam sij. Koj tuaj yeem txav ib lub rooj mus rau lwm pab pawg los ntawm kev tsim cov ntaub ntawv sib txuas ntawm ib pawg file sib txawv. Koj tsis tas yuav tso lub rooj li koj xav txav ib heap.
