Cov txheej txheem:
Video: Vim li cas cov lus hais kom poob hauv SQL siv?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
SQL DROP nqe lus
Cov SQL DROP hais kom ua yog siv rau tshem tawm ib yam khoom los ntawm database . Yog koj poob a rooj , tag nrho cov kab hauv lub rooj yog deleted thiab rooj qauv raug tshem tawm ntawm lub database . Ib zaug ib rooj yog poob peb tsis tuaj yeem rov qab tau, yog li ceev faj thaum siv DROP command.
Tom qab ntawd, ib tug kuj yuav nug, dab tsi yog lub hom phiaj ntawm lub rooj hais kom ua hauv SQL?
Cov SQL DROP TABLE nqe lus yog siv rau tshem tawm a rooj txhais thiab tag nrho cov ntaub ntawv, indexes, triggers, txwv thiab tso cai specifications rau qhov ntawd rooj.
Tsis tas li ntawd, qhov sib txawv ntawm kev rho tawm thiab tso cov lus txib hauv SQL yog dab tsi? Cov DROP command tshem tawm ib lub rooj los ntawm database. Tag nrho cov kab lus, qhov ntsuas, thiab cov cai tseem yuav raug tshem tawm. DROP thiab TRUNCATE yog DDL lus txib , hos DELETE yog DML lus txib . DELETE kev ua haujlwm tuaj yeem dov rov qab (undone), thaum DROP thiab TRUNCATE cov haujlwm tsis tuaj yeem thim rov qab.
Khaws qhov no hauv kev txiav txim siab, ua li cas koj tso lub rooj hauv SQL yog tias nws muaj?
SQL Server DROP TABLE
- Ua ntej, qhia lub npe ntawm lub rooj yuav raug tshem tawm.
- Qhov thib ob, qhia lub npe ntawm cov ntaub ntawv uas lub rooj tau tsim thiab lub npe ntawm lub schema uas lub rooj koom nrog. Lub npe database yog xaiv tau.
- Thib peb, siv IF EXISTS clause kom tshem tawm lub rooj tsuas yog tias nws muaj.
Kuv yuav rho tawm lub rooj hauv database li cas?
Txhawm rau rho tawm ib lub rooj los ntawm database
- Hauv Object Explorer, xaiv lub rooj koj xav rho tawm.
- Right-click lub rooj thiab xaiv Delete los ntawm shortcut menu.
- Ib lub thawv ntawv qhia koj kom paub meej tias kev tshem tawm. Nyem Yog. Rho tawm lub rooj cia li tshem tawm kev sib raug zoo rau nws.
Pom zoo:
Dab tsi ntawm cov hauv qab no yog qhov zoo ntawm kev siv cov khoom siv pom kev hauv kev hais lus?
Qhov txiaj ntsig tseem ceeb ntawm kev siv cov khoom siv pom hauv koj cov lus hais yog tias lawv ua kom cov neeg tuaj saib muaj kev txaus siab, hloov kev mloog ntawm tus neeg hais lus, thiab ua rau tus neeg hais lus muaj kev ntseeg siab ntau dua hauv kev nthuav qhia tag nrho
Dab tsi ntawm cov hauv qab no hais txog lub peev xwm ntawm cov khoom siv computer lossis cov kab ke nthuav dav los pab ntau tus neeg siv yam tsis tau tawg?
Scalability hais txog lub peev xwm ntawm lub khoos phis tawj, cov khoom lag luam, lossis cov txheej txheem nthuav dav los pab ntau tus neeg siv yam tsis muaj kev tawg. IT infrastructure tsuas yog cov cuab yeej siv lub cev tsuas yog xav tau los khiav lag luam
Kuv yuav ua li cas khiav Java program hauv Windows 10 siv cov lus hais kom ua?
2 Cov Lus Teb Tshawb xyuas koj txoj hauv kev javac ntawm Windows siv Windows Explorer C:Program FilesJavajdk1. 7.0_02in thiab luam qhov chaw nyob. Mus rau Control Vaj Huam Sib Luag. Environment Variables thiab Ntxig qhov chaw nyob ntawm qhov pib ntawm var. Kaw koj cov lus txib tam sim thiab rov qhib nws, thiab sau cov cai rau kev suav sau thiab ua tiav
Vim Li Cas Peb Siv mount hais kom ua hauv Linux?
Linux mount hais kom ua thauj cov ntaub ntawv ntawm USBs, DVDs, SD phaib, thiab lwm yam khoom siv khaws cia ntawm lub khoos phis tawj khiav Linux operating system. Linux siv cov ntawv teev npe ntoo. Tshwj tsis yog tias cov cuab yeej khaws cia yog txuas rau cov qauv ntoo, tus neeg siv tsis tuaj yeem qhib ib qho ntawm cov ntaub ntawv hauv lub computer
Lub sij hawm nyob rau hauv ontology yog dab tsi yog hais txog cov lus piav qhia hierarchical thiab cov lus hais txog ib qho tshwj xeeb?
Lub schema yog ib lo lus ontology uas hais txog cov lus piav qhia hierarchical thiab cov lus hais txog ib lub npe. Ib lub npe sawv cev rau tag nrho lub tuam txhab lossis kev faib hauv ib lub tuam txhab. Ib tug cwj pwm yog ib tug yam ntxwv tshwj xeeb hais txog ib chav kawm, uas yog ib hom khoom