Video: Index yog dab tsi thiab tsim index hauv SQL?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
SQL CREATE INDEX Nqe lus. Cov CREATE INDEX nqe lus yog siv rau tsim indexes hauv rooj. Index yog siv los retrieve cov ntaub ntawv los ntawm database sai dua li lwm yam. Nco tseg: Hloov kho lub rooj nrog indexes siv sijhawm ntau dua li hloov kho lub rooj tsis muaj (vim lub indexes kuj xav tau kev hloov tshiab).
Tsuas yog li ntawd, dab tsi yog qhov ntsuas hauv SQL?
SQL ntawv - Index. Kev tshaj tawm. Indexs yog cov rooj saib tshwj xeeb uas lub tshuab tshawb nrhiav database tuaj yeem siv los ua kom ceev cov ntaub ntawv rov qab. Yooj yim muab, ib qhov ntsuas yog tus taw tes rau cov ntaub ntawv hauv lub rooj. Ib qhov ntsuas nyob rau hauv ib tug database yog heev zoo ib yam li ib qhov ntsuas hauv qab ib phau ntawv.
Qhov thib ob, qhov Performance index yog dab tsi hauv SQL Server nrog piv txwv? A SQL Server Index yog siv rau ntawm lub rooj database kom ceev cov ntaub ntawv nkag.
Ntxig thiab Hloov Kho nrog Cov Tsis-clustered Index.
| Clustered Index | Tsis-Clustered Index |
|---|---|
| Qhov no yuav npaj cov kab hauv lub cev hauv lub cim xeeb hauv kev txheeb xyuas | Qhov no yuav tsis npaj cov kab hauv lub cev hauv lub cim xeeb hauv kev txheeb xyuas. |
Hais txog qhov no, koj ua li cas los tsim ib qho kev ntsuas hauv ib lub rooj?
Lub syntax rau tsim ib qho index yog: CREATE INDEX "index_name" RAU "table_name" (column_name); Nco ntsoov tias ib qhov ntsuas tuaj yeem npog ib qho xwb rooj . Peb ua tsis tau tsim ib qho index uas npog ntau yam rooj.
Thaum twg peb yuav tsum tsim qhov ntsuas hauv SQL?
Yog tias database loj yog qhov kev txhawj xeeb tseem ceeb, koj yuav tsum tsim indexes me ntsis. Data distribution Yog ib qhov ntsuas lookup rov qab muaj nuj nqis ntau dhau lawm, nws yog nqi ntau dua li ib qho kev soj ntsuam ua ntu zus. SQL ntawv Txhua qhov chaw tsis siv cov qhov ntsuas thaum nws paub txog tus mob no.
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