Video: Dab tsi yog Boolean cov ntaub ntawv hom hauv SQL Server?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
A boolean yog a hom ntaub ntawv uas tuaj yeem khaws qhov tseeb lossis qhov tsis tseeb. Qhov no feem ntau khaws cia li 1 (tseeb) lossis 0 (tsis tseeb). Nws muaj npe tom qab George Boole uas thawj zaug txhais ib qho kev ua lej ntawm cov logic hauv xyoo pua 19th.
Tsuas yog li ntawd, puas muaj Boolean datatype hauv SQL?
Nyob ntawd yog boolean cov ntaub ntawv hom hauv SQL Server. Nws qhov tseem ceeb tuaj yeem yog TRUE, FALSE lossis UNKNOWN. Txawm li cas los xij, hom ntaub ntawv boolean yog xwb tus tshwm sim a boolean kev nthuav qhia uas muaj qee qhov sib xyaw ua ke ntawm cov neeg ua haujlwm sib piv (piv txwv li =,, =) lossis cov neeg siv cov lus qhia (piv txwv li THIAB, LOSSIS, IN, EXISTS).
Tsis tas li ntawd, Boolean yog dab tsi hauv database? Boolean cov neeg ua haujlwm tsim lub hauv paus ntawm kev ua lej thiab database logic. Lawv txuas koj cov lus tshawb fawb ua ke kom nqaim lossis nthuav koj cov txiaj ntsig. Peb qhov yooj yim boolean Cov neeg ua haujlwm yog: THIAB, LOSSIS, thiab TSIS TAU.
Qhov thib ob, hom ntaub ntawv Boolean siv rau dab tsi?
BOOLEAN tuaj yeem yog siv as a hom ntaub ntawv thaum txhais a kem hauv ib lub rooj los yog ib sib txawv hauv cov txheej txheem database. Kev them nyiaj yug rau lub BOOLEAN cov ntaub ntawv hom pab kev tsiv teb tsaws chaw los ntawm lwm cov khoom siv database. Boolean txhua kab lees txais raws li kev nkag mus rau SQL literals FALSE thiab TRUE.
Boolean tus nqi SQL yog dab tsi?
Loj SQL ntawv 1.0 - Boolean tus nqi . A tus nqi boolean sawv cev qhov tseeb tus nqi . Cov BOOLEAN hom yog 1-byte tus nqi uas qhia tias muaj tseeb, cuav, los yog null. Boolean tuaj yeem muab pov rau lossis los ntawm cov cim cov ntaub ntawv uas muaj "tseeb" lossis "false." Hauv kev sib sau ua ke, "tseeb" xaiv siab dua "tsis tseeb."
Pom zoo:
Cov ntaub ntawv hom thiab cov qauv ntaub ntawv yog dab tsi?
Cov qauv ntaub ntawv yog ib txoj hauv kev piav qhia txog ib txoj hauv kev los npaj cov ntaub ntawv kom ua haujlwm andalogrithms tuaj yeem siv tau yooj yim dua. Ib hom ntaub ntawv piav qhia txog cov ntaub ntawv uas txhua tus sib koom ua ke. Piv txwv li tus lej cov ntaub ntawv hom piav qhia txhua tus lej uas lub khoos phis tawj tuaj yeem ua tau
Dab tsi yog lub hom phiaj ntawm delimiters nyob rau hauv cov ntawv sau npe ob hom ntawv cov ntaub ntawv delimiters?
Cov ntaub ntawv delimited yog cov ntawv nyeem siv los khaws cov ntaub ntawv, uas txhua kab sawv cev rau ib phau ntawv, tuam txhab, lossis lwm yam, thiab txhua kab muaj cov teb sib cais los ntawm tus lej
Dab tsi yog hom ntawv cov ntaub ntawv hauv SQL Server?
Nws yog Non-Unicode loj sib txawv ntev lub cim cov ntaub ntawv hom, uas tuaj yeem khaws qhov siab tshaj plaws ntawm 2147483647 Cov Cim Tsis-Unicode (piv txwv li qhov muaj peev xwm cia siab tshaj plaws yog: 2GB). Version ntawm Sql Server nyob rau hauv uas nws tau qhia? Cov ntaub ntawv hom yog tam sim no los ntawm cov qub versions ntawm Sql Server
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
Dab tsi yog cov teeb meem ntawm kev tswj cov ntaub ntawv hauv cov ntaub ntawv ib txwm muaj?
Nyob rau tib lub sijhawm, qhov kev tswj hwm cov ntaub ntawv ib puag ncig tsim teeb meem xws li cov ntaub ntawv rov ua dua thiab tsis sib xws, cov kev pab cuam-cov ntaub ntawv dependence, inflexibility, tsis muaj kev ruaj ntseg, thiab tsis muaj cov ntaub ntawv sib qhia thiab muaj