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Kuv yuav xaiv cov ntaub ntawv duplicate hauv MySQL li cas?
Kuv yuav xaiv cov ntaub ntawv duplicate hauv MySQL li cas?

Video: Kuv yuav xaiv cov ntaub ntawv duplicate hauv MySQL li cas?

Video: Kuv yuav xaiv cov ntaub ntawv duplicate hauv MySQL li cas?
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Nrhiav qhov tseem ceeb dua nyob rau hauv ib kem ntawm ib lub rooj, koj siv ua raws li cov kauj ruam no:

  1. Ua ntej, siv GROUP BY clause los pab pawg tag nrho kab los ntawm lub hom phiaj kab, uas yog kab uas koj xav mus xyuas luam tawm .
  2. Tom qab ntawd, siv COUNT() ua haujlwm hauv HAVING clause los xyuas seb ib pawg twg muaj ntau tshaj 1 lub ntsiab lus.

Ua raws li qhov no saib, kuv yuav ua li cas tso saib tsuas yog cov ntaub ntawv duplicate hauv SQL?

Xaiv count(*) AS count_, favorite_color_ FROM person_ GROUP BY favorite_color_ HAVING count(*) > 1 ORDER BY count_ DESC; Cov suav (*) hais kom ua yog ib qho kev ua haujlwm sib sau txhawb nqa los ntawm Postgres thiab muab cov naj npawb ntawm kab nrog duplicate nqi nyob rau hauv ib kem teev los ntawm GROUP BY clause.

Tom qab ntawd, lo lus nug yog, yuav ua li cas thiaj li tshem tau cov kab duplicate? Tshem tawm cov nqi sib npaug

  1. Xaiv qhov ntau ntawm cov cell, los yog xyuas kom meej tias lub cell active nyob rau hauv ib lub rooj.
  2. Ntawm cov ntaub ntawv tab, nyem Tshem Tawm Duplicates.
  3. Nyob rau hauv lub Remove Duplicates dialog box, unselect tej kab uas koj tsis xav kom tshem tawm duplicate nqi.
  4. Nyem OK, thiab cov lus yuav tshwm sim los qhia tias muaj pes tsawg tus nqi duplicate raug tshem tawm.

Yog li ntawd, kuv tuaj yeem rho tawm cov ntaub ntawv duplicate hauv mysql li cas?

Tsim ib lub rooj tshiab nrog cov qauv zoo ib yam li cov lus qub uas koj xav tau rho tawm duplicate kab . Ntxig qhov txawv kab los ntawm thawj lub rooj mus rau lub rooj tam sim. Tso lub rooj qub thiab hloov lub npe tam sim ntawd rau lub rooj qub.

Kuv yuav nrhiav tau cov duplicates hauv SQL li cas?

Nws ua haujlwm li cas:

  1. Ua ntej, GROUP BY clause pab pawg kab rau hauv pab pawg los ntawm qhov tseem ceeb hauv ob kab a thiab b.
  2. Qhov thib ob, COUNT() muaj nuj nqi rov qab tus naj npawb ntawm qhov tshwm sim ntawm txhua pab pawg (a, b).
  3. Thib peb, HAVING clause khaws tsuas yog pawg sib npaug, uas yog pawg uas muaj ntau dua ib qho tshwm sim.

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