Qinisekisa ukuthembeka kweDatha yakho
Isizinda sedatha yedatha, ngokulula kwayo, yiluhlobo lwedatha olusetshenziswa ikholomu ku-database. Lolu hlobo lwedatha lungaba uhlobo olwakhiwe (njenge-integer noma intambo) noma uhlobo lwendabuko oluchaza izithiyo kule data.
Ukungena kwedatha nezizinda
Uma ufaka idatha kwifomu le-intanethi yanoma yiluphi uhlobo - kungakhathaliseki ukuthi yigama lakho nje ne-imeyili, noma isicelo esiphelele somsebenzi - i-database igcina ukufaka kwakho ngemuva kwezigcawu. Leyo datha ihlola okufakiwe kwakho ngokusekelwe kuhlelo lokusetha. Isibonelo, uma ufaka ikhodi ye-zip, i-database ilindele ukuthola izinombolo ezinhlanu, noma ikhodi ephelele yase-US: izinombolo ezinhlanu zilandelwa i-hyphen, bese izinombolo ezine. Uma ufaka igama lakho ku-zip code field, i-database ingase ikhononde.
Kungenxa yokuthi i-database ihlola ukungena kwakho ngokumelene nesizinda esichazwe kwenkambu ye-zip. Isizinda ngokuyinhloko uhlobo lwedatha olungabandakanya imikhawulo yokuzikhethela.
Ukuqonda Domain Database
Ukuqonda isizinda sedatha, ake sicabangele ezinye izici ezimbalwa ze-database:
- I-database yolwazi ichaza isethi yezimfanelo , ezibizwa nangokuthi amakholomu noma amasimu. Isibonelo, uma unetafula "Imininingwane Yokuxhumana Yomsebenzi," ingase ihlanganise izimfanelo ze-FirstName, LastName, JobTitle, StreetAddress, City, State, ZipCode, UcingoNumber kanye ne-Imeyili.
- Isici ngasinye sinesizinda esichaza amanani avumelekile. Lokhu kungafaka uhlobo lwedatha, ubude, amanani kanye neminye imininingwane.
Isibonelo, isizinda se-ZipCode yemfanelo singacacisa uhlobo lwezinombolo zezinombolo, njenge-integer, evame ukubizwa nge-INT noma i-INTEGER, kuye ngokuthi imininingwane. Noma umklami wezinqolobane angase akhethe ukuyichaza esikhundleni sakhe njengohlamvu, ngokuvamile ebizwa ngokuthi i-CHAR. Imfanelo ingachazwa kabanzi ukuze idinga ubude obuthile, noma ngabe inani elingenalutho noma elingaziwa livumelekile.
Uma ubutha ndawonye zonke izakhi ezichaza isizinda, usuphetha ngohlobo oluthile lwedatha, olubizwa nangokuthi "uhlobo lwedatha oluchazwe ngumsebenzisi" noma i-UDT.
Mayelana nobuqotho besizinda
Amanani avunyelwe we-attribute akha ubuqotho besizinda , okuqinisekisa ukuthi yonke idatha ensimini iqukethe amanani asebenzayo.
Ubuqotho besizinda buchazwa ngu:
- Uhlobo lwedatha, njenge-integer, uhlamvu noma i-decimal
- Ubude obuvunyelwe kwedatha
- Ububanzi, ukuchaza imingcele engenhla nephansi
- Noma yiziphi izithiyo , noma ukulinganiselwa kumanani avumelekile. Isibonelo, insimu yekhodi ye-zip yase-US ingase iqine ikhodi ephelele ye-ZIP + 4 , noma ikhodi ephelele yamadijithali ayisishiyagalolunye.
- Uhlobo lwenkokhelo ye-NULL, noma ngabe imfanelo ingaba nokungaziwa, noma inani le-NULL
- Inani elizenzakalelayo, uma likhona
- Ifomethi yosuku, uma kusebenza (isibonelo, dd / mm / yy noma mm / dd / yyyy)
Ukwakha i-Domain
Ngokuba yolwazi olusebenzisa i- SQL (Ulimi Lokusebenza Oluhlelekile) noma i-flavour ye-SQL, sebenzisa umyalo we-CREATE DOMAIN SQL.
Isibonelo, isitatimende sokwenziwa lapha sikhiqiza isici se-ZipCode sohlobo lwedatha ye-CHAR ngezinhlamvu ezinhlanu. I-NULL, noma inani elingaziwa, alivumelekile. Ububanzi bwedatha kumele buwe phakathi kwe- "00000" no "99999." kudala isici se-ZipCode sohlobo lwedatha ye-CHAR ngezinhlamvu ezinhlanu. I-NULL, noma inani elingaziwa, alivumelekile. Ububanzi bwedatha kumele buwe phakathi kwe- "00000" no "99999."
Dala i-DOMAIN i-ZipCode CHAR (5) AKUKHULU KWE-NULL (VALUE> '00000' NOKUBALULEKA
Yonke uhlobo lwe-database lunikeza indlela yokuchaza isethi yemingcele nemithetho elawula idatha engavumelekile, ngisho noma ingayibambi isizinda. Bheka amadokhumende wakho wedatha ukuze uthole imininingwane.