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Dab tsi yog nrum hauv SQL query?
Dab tsi yog nrum hauv SQL query?

Video: Dab tsi yog nrum hauv SQL query?

Video: Dab tsi yog nrum hauv SQL query?
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Hauv SQL ntawv Server (Kev hloov pauv- SQL ntawv ), cov CAST function converts ib qho kev qhia los ntawm ib datatype mus rau lwm datatype. Yog hais tias qhov kev hloov dua siab tshiab tsis ua haujlwm, cov haujlwm yuav rov qab ua qhov yuam kev. Txwv tsis pub, nws yuav rov qab tau tus nqi hloov dua siab tshiab. TSWV YIM: Siv TRY_CAST muaj nuj nqi kom rov qab NULL (tsis yog qhov yuam kev) yog tias qhov hloov pauv tsis ua tiav.

Hais txog qhov no, cas cast txhais li cas hauv SQL?

Cov CAST ua haujlwm hauv SQL ntawv converts cov ntaub ntawv los ntawm ib hom ntaub ntawv mus rau lwm tus. Piv txwv li, peb tuaj yeem siv cov CAST muaj nuj nqi los hloov cov ntaub ntawv tus lej rau hauv cov ntaub ntawv kab cim.

Ib tug kuj yuav nug, yuav ua li cas kuv cam khwb cia li decimal nyob rau hauv SQL? Summary: nyob rau hauv no nyeem, koj yuav kawm paub siv cov SQL ntawv Server CAST () ua haujlwm los hloov tus nqi lossis ib qho kev qhia los ntawm ib hom mus rau lwm qhov.

B) Kev siv lub tshuab CAST () muaj nuj nqi los hloov a kaum tsib rau lwm tus kaum tsib nrog qhov ntev sib txawv.

Los ntawm Data Type Rau Data Type Cwj pwm
tus lej int Txiav tawm
tus lej nyiaj Hloov

Kuj Paub, qhov txawv ntawm cam khwb cia thiab hloov pauv hauv SQL yog dab tsi?

CAST thiab CONVERT yog ob SQL ntawv functions siv los ntawm programmers rau hloov ib hom ntaub ntawv mus rau lwm tus. Cov CAST muaj nuj nqi yog siv rau hloov hom ntaub ntawv tsis muaj hom ntawv tshwj xeeb. Cov Hloov pauv muaj nuj nqi hloov dua siab tshiab thiab formatting hom ntaub ntawv tib lub sijhawm.

Yuav ua li cas kuv nrum hnub hauv SQL?

Yuav ua li cas kom tau txais ntau hom SQL Server hnub tim

  1. Siv cov kev xaiv hnub hom nrog rau CONVERT muaj nuj nqi.
  2. Kom tau txais YYYY-MM-DD siv SELECT CONVERT(varchar, getdate(), 23)
  3. Kom tau MM/DD/YYYY siv SELECT CONVERT(varchar, getdate(), 1)
  4. Tshawb xyuas daim ntawv qhia kom tau txais cov npe ntawm txhua hom kev xaiv.

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