Vim li cas cov lus nug parameterized muaj kev nyab xeeb?
Vim li cas cov lus nug parameterized muaj kev nyab xeeb?

Video: Vim li cas cov lus nug parameterized muaj kev nyab xeeb?

Video: Vim li cas cov lus nug parameterized muaj kev nyab xeeb?
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Parameterized queries ua kom raug hloov ntawm kev sib cav ua ntej khiav SQL nug . Nws tshem tawm tag nrho qhov muaj peev xwm ntawm "kev qias neeg" cov tswv yim hloov lub ntsiab lus ntawm koj nug . Ntawd yog, yog tias cov tswv yim muaj SQL, nws tsis tuaj yeem dhau los ua ib feem ntawm qhov ua tiav vim tias SQL yeej tsis raug txhaj rau hauv cov lus qhia.

Ntxiv rau qhov no, cov lus nug parameterized txhais li cas?

A parameterized lus nug (tseem hu ua ib nqe lus npaj) yog a txhais tau tias ntawm pre-compiling a SQL ntawv nqe lus kom txhua yam koj xav tau muab yog cov "parameters" (xav tias "variables") uas yuav tsum tau muab tso rau hauv nqe lus rau nws yuav tsum tau ua. Nws yog feem ntau siv raws li ib tug txhais tau tias ntawm kev tiv thaiv SQL ntawv txhaj tshuaj tiv thaiv.

Qhov thib ob, yuav ua li cas raws nraim cov lus nug parameterized pab tiv thaiv los ntawm SQL txhaj? Parameterized queries ua kom raug hloov ntawm cov lus sib cav ua ntej khiav qhov SQL lus nug . Nws tshem tawm tag nrho qhov muaj peev xwm ntawm "qhuav" cov tswv yim hloov lub ntsiab lus ntawm koj nug . Uas yog, yog hais tias cov tswv yim muaj SQL ntawv , nws tsis tuaj yeem dhau los ua ib feem ntawm qhov raug tua vim qhov SQL ntawv yeej tsis txhaj rau hauv nqe lus uas tshwm sim.

Tom qab ntawd, cov lus nug parameterized puas muaj kev nyab xeeb los ntawm SQL txhaj?

Tej yam dynamic SQL lus nug tsim siv invalidated neeg siv inputs yog yooj yim rau SQL txhaj . Qee txoj hauv kev tsim tawm siv los txhawm rau tiv thaiv SQL txhaj yog parameterized cov lus nug lossis cov txheej txheem khaws cia. A parameterized lus nug yog feem ntau ruaj ntseg tawm tsam SQL Txhaj kev tawm tsam.

Lub hom phiaj ntawm cov lus nug parameter yog dab tsi?

A parameter lus nug yog ib qho ntawm qhov yooj yim tshaj plaws thiab muaj txiaj ntsig zoo tshaj plaws lus nug koj tuaj yeem tsim. Nws tso cai rau koj los tsim ib qho nug uas tuaj yeem hloov kho yooj yim los cuam tshuam cov lus tshawb nrhiav tshiab. Thaum koj qhib a parameter lus nug , Kev nkag mus yuav ceeb toom koj rau lub sijhawm tshawb nrhiav thiab tom qab ntawd qhia koj nug cov txiaj ntsig uas cuam tshuam koj qhov kev tshawb nrhiav.

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