Cov txheej txheem:
Video: Cov nqe lus CASE ua haujlwm li cas?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
CASE Statement . Cov CASE lus xaiv los ntawm ib theem zuj zus ntawm tej yam kev mob, thiab executes ib tug coj nqe lus . Cov CASE lus ntsuas ib qho kev qhia thiab muab piv rau ntau qhov muaj peev xwm, lossis ntsuas ntau yam Boolean kab lus thiab xaiv thawj tus uas yog TRUE.
Ib yam li ib tug yuav nug, CASE nqe lus ua haujlwm li cas hauv SQL?
Cov SQL CASE Statement Cov CASE lus mus los ntawm cov xwm txheej thiab rov qab tus nqi thaum thawj qhov xwm txheej tau ntsib (zoo li IF-THEN-ELSE nqe lus ). Yog li, ib zaug ib qho xwm txheej muaj tseeb, nws yuav tsum tsis nyeem ntawv thiab rov qab cov txiaj ntsig. Yog tias tsis muaj cov xwm txheej muaj tseeb, nws rov qab tus nqi hauv ELSE clause.
Ib sab saum toj no, cov lus hloov pauv ua haujlwm li cas? A nqe lus hauv hloov thaiv tuaj yeem sau nrog ib lossis ntau dua cas los yog default labels. Cov hloov nqe lus ntsuam xyuas nws cov lus qhia, ces executes tag nrho nqe lus uas ua raws li kev sib tw cas daim ntawv lo.
Ua li no, koj yuav sau ib nqe lus li cas?
Yog li Koj Yuav Tsum Sau Cov Lus Qhia Txog Tus Kheej: Ib Daim Ntawv Qhia Tseem Ceeb rau Qhia Koj Cov Ntaub Ntawv
- KAUJ RUAM 1: Kev Taw Qhia. Zoo li feem ntau cov ntaub ntawv, cov ntaub ntawv hais txog qhov yuav tsum tau muaj kev taw qhia muaj zog.
- Kauj Ruam 2: Koj Lub Zeem Muag.
- KAUJ RUAM 3: Kev Sib Tw.
- KAUJ RUAM 4: Tus Neeg Pab Tswv Yim.
- KAUJ RUAM 5: Txhawb nrog Qhov Tseeb + Txhim Kho Nrog Kev Pom Zoo.
Peb puas tuaj yeem siv cov lus xaiv hauv rooj plaub?
CASE lus hauv SQL. Cov case lus hauv SQL xa rov qab tus nqi ntawm ib qho xwm txheej. Peb tuaj yeem siv tau a Case lus hauv xaiv queries nrog rau qhov twg, Order By thiab Group By clause. Nws ua tau siv rau hauv Insert nqe lus ib yam nkaus.
Pom zoo:
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