Video: JSON tuaj yeem khaws cov haujlwm?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Tsis muaj muaj nuj nqi ntaus ntawv hauv JSON . JSON txhawb nqa khoom, arrays, hlua, lej, booleans thiab null. Nws yog hom ntaub ntawv, tsis yog hom lus programming. Nws tsis muaj txiaj ntsig ntau rau nws txhawb nqa kev ua haujlwm.
Ntawm no, JSON puas tuaj yeem muaj haujlwm?
Cov lus teb yog: Tsis yog, nws tsis siv tau los txhais kev ua haujlwm hauv JSON tshwm sim! Txawm tias JSON yog siv los ua hom lus ywj pheej cov ntaub ntawv serialization, ib qho kev sib txuas ntawm "code" los ntawm lwm hom yuav ua haujlwm. A JSON txoj hlua yuav raug siv los hla JS muaj nuj nqi mus rau tus neeg siv-sab browser rau kev ua tiav.
Qhov thib ob, JSON yuam sij tuaj yeem yog tus lej? JSON tsuas tso cai tus yuam sij cov npe los ua cov hlua. Koj tsis siv JSON txawm tias. Koj muaj JavaScript object literal. Koj ua tau siv identifiers rau yuam sij , tab sis tus ID ua tau 'tsis pib nrog a tus lej.
Tom qab ntawd, siv JSON Stringify yog dab tsi?
Cov JSON . stringify method converts tus nqi JavaScript rau hauv a JSON txoj hlua. Nws yog feem ntau siv los hloov JavaScript arrays lossis khoom rau JSON , txawm tias nws tuaj yeem ua tau siv nrog cov ntaub ntawv yooj yim xws li cov hlua thiab cov lej.
Puas yog JSON yog hom lus programming?
JSON yog ib hom ntaub ntawv. Nws tuaj yeem raug cais ua ib qho lus , tab sis tsis yog a programming lus . Nws txoj kev sib raug zoo rau JavaScript yog tias nws qhia nws cov syntax (ntau dua lossis tsawg dua) nrog cov txheej txheem ntawm JavaScript literals. Cov JSON specification txhais nws kiag li; nws tsis yog nyob ntawm kev xa mus rau JavaScript specification.
Pom zoo:
Cov lag luam feem ntau txhim kho dab tsi tuaj yeem khaws thiab txheeb xyuas cov ntaub ntawv rau lub hom phiaj ntawm kev txiav txim siab ua lag luam?
Cov lag luam feem ntau txhim kho dab tsi tuaj yeem khaws thiab txheeb xyuas cov ntaub ntawv rau lub hom phiaj ntawm kev txiav txim siab ua lag luam? kev khiav hauj lwm qhov system. Ib lub hom phiaj ntawm kev tswj cov ntaub ntawv yog muab cov lag luam nrog cov ntaub ntawv zoo uas lawv xav tau: ua kom tiav ib txoj haujlwm
Ntev npaum li cas cov ntaub ntawv tuaj yeem khaws cia hauv cov ntaub ntawv warehouse?
10 xyoo Yog li ntawd, cov ntaub ntawv khaws cia hauv lub tsev khaws ntaub ntawv li cas? Cov ntaub ntawv yog feem ntau khaws cia rau hauv ib lub tsev khaws ntaub ntawv los ntawm cov txheej txheem rho tawm, hloov pauv thiab thauj khoom (ETL), qhov twg cov ntaub ntawv tau muab rho tawm los ntawm qhov chaw, hloov mus rau qhov zoo cov ntaub ntawv thiab ces loaded rau hauv ib lub tsev khaws khoom .
Dab tsi yog array peb tuaj yeem khaws cov hlua thiab cov lej ua ke hauv ib qho array?
Arrays tuaj yeem muaj txhua yam khoom muaj nqis (hom qub lossis khoom), tab sis koj tsis tuaj yeem khaws ntau hom hauv ib qho array. Koj tuaj yeem muaj array ntawm tus lej lossis ib qho array ntawm cov hlua lossis ib qho array ntawm arrays, tab sis koj tsis tuaj yeem muaj ib qho array uas muaj, piv txwv li, ob txoj hlua thiab cov lej
Vim li cas kem taw qhia cov ntaub ntawv khaws cia ua cov ntaub ntawv nkag ntawm disks sai dua li kab qhia cov ntaub ntawv khaws cia?
Kem oriented databases (aka columnar databases) yog qhov tsim nyog rau kev ntsuas kev ua haujlwm ntau dua vim tias cov ntaub ntawv hom ntawv (kem hom) qiv nws tus kheej kom nrawm dua cov lus nug ua - scans, aggregation thiab lwm yam. Ntawm qhov tod tes, kab oriented databases khaws ib kab (thiab tag nrho nws. kab) contiguously
Koj tuaj yeem siv cov txheej txheem khaws cia thiab lossis ua rau cov ntaub ntawv no li cas?
Peb tuaj yeem ua tiav cov txheej txheem khaws cia thaum twg peb xav tau nrog kev pab los ntawm exec hais kom ua, tab sis qhov tshwm sim tsuas yog raug tua thaum twg ib qho kev tshwm sim (ntxig, rho tawm, thiab hloov tshiab) raug rho tawm haujlwm ntawm lub rooj uas txhais tau hais tias. Cov txheej txheem khaws cia tuaj yeem coj cov kev nkag tsis tau, tab sis peb tsis tuaj yeem hla tsis tau raws li kev nkag mus rau qhov tshwm sim