Ixazululiwe: inkomba yokudonsa ye-sql

I-Oracle SQL iwulimi lokuhlela olunamandla olusetshenziselwa ukuphatha amasistimu okuphatha imininingwane egciniwe (RDBMS). Namuhla, sizocubungula ngokujulile umqondo othile - umyalo we-SQL Drop Index.

I-Index ku-SQL isetshenziselwa ukusheshisa ukubuyiswa kwemigqa ngokusebenzisa i-pointer. Kuyinto yesizindalwazi edalwe kuthebula elikhona ukuze kusheshiswe inqubo yokubuyisa imigqa. Nokho, nakuba kunenzuzo, kungase kube nezidingo zokwehlisa inkomba. Isitatimende se-SQL DROP INDEX sisetshenziselwa ukwenza lokhu futhi sisiza ekususeni inkomba kuthebula.

Umyalo we-SQL DROP INDEX

Umyalo we-SQL DROP INDEX uwumsebenzi we-DDL (Data Definition Language) osetshenziselwa ukumaka inkomba ukuze isuswe ngokukhipha inkomba yento eyodwa noma ngaphezulu engadingekile kusichazamazwi sesizindalwazi. Lokhu kungaba yinzuzo ukukhulula isikhala esithile ohlelweni noma lapho inkomba ingasadingeki. I-syntax ye-SQL yalokhu ilula kakhulu:

DROP INDEX index_name;

Lapho elithi 'index_name' kuyigama lenkomba ohlose ukuyiyeka.

Sicela ukhumbule, ngenkathi usebenzisa isitatimende se-DROP INDEX, cabanga ukuthi singaba nomthelela omubi ekusebenzeni kwe-SQL uma inkomba isetshenziswa kakhulu ekubuyiseni imibuzo. Ukuqonda uhlelo kanye nezidingo zalo kubalulekile ngenkathi ubhekene nezinkomba zokwehla.

Isinyathelo ngesinyathelo Ukwenziwa komyalo we-DROP INDEX

Ukuze siqonde kangcono, ake sidlule ekwenzeni isinyathelo ngesinyathelo sokudala, sisebenzisa bese silahla inkomba ku-Oracle SQL.

  • Ake sicabange ukuthi sinetafula elibizwa ngokuthi 'Amakhasimende' elinekholomu 'ye-Custom_id' phakathi kwamanye. Isinyathelo sokuqala siwukwenza inkomba kule kholomu ye-'Customer_id' uma ingekho kakade. Umyalo walokhu uthi
    DALA INDEX idx_customer
    KUMAmakhasimende (Customer_id);
  • Manje, cabanga ukuthi imisebenzi eminingi yenziwa kusetshenziswa le nkomba. Kancane kancane, uhlelo luphawula ukuthi le nkomba ayisadingeki.
  • Ukuze uwise inkomba, umyalo we-DROP INDEX usetshenziswa.
    YEHLISA ISIHLOKO idx_customer;

Uma isikhishiwe, inkomba ethi 'idx_customer' izokwehliswa kuthebula elithi 'Amakhasimende' futhi isikhala esisetshenziswe yiyo sizokhishwa.

Ehlobene SQL Concepts

Ngaphandle kwesitatimende se-DROP INDEX, kuneminye imiyalo ye-DDL ku-SQL enomthelela ekuphatheni isizindalwazi ngempumelelo:

DALA INDEX: Lo myalo usetshenziselwa ukwakha inkomba kumakholomu ethebula.

NGESINYE ISIKHOMBISI: Isitatimende se-ALTER INDEX silungisa inkomba ekhona noma izici zayo. Ushintsho lungaba ukwakha kabusha, ukuqamba kabusha, ukunika amandla noma ukukhubaza inkomba.

Ukusebenza kwe-SQL nokuphathwa kwesikhala kungaba isici esiyinselele sokuphatha isizindalwazi. Ukusetshenziswa ngempumelelo kwemiyalo ye-DDL efana ne-DROP INDEX, uma kucatshangelwa izidingo zesistimu, kungasiza kakhulu ekufinyeleleni ukusebenza kahle. Hlala ukhumbula ukuhlola kabili ukusetshenziswa kwale miyalo njengoba ingaba nomthelela omkhulu kusizindalwazi.

Okuthunyelwe okuhlobene:

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