Iva nechokwadi chekuti Dharedhi Dzako Dzakatendeseka
A database database, pazviri nyore, iyo data dhiyabhorosi inoshandiswa nekorodhe mune database. Iyi nhamba yedhesi inogona kuva yakagadzirwa mukati (yakadai sewe integer kana tambo) kana rudzi rwetsika runotsanangura zvinetso pa data.
Dhipatimendi reDhina uye Domains
Paunopinda dhamusi mune imwe nzvimbo yepaIndaneti yemhando ipi zvayo-ingava zita rako chete uye email, kana basa rakazara rekushanda - dhesikisi inochengetedza zvaunofunga mushure memaonero. Dhiyabhorosi iyo inotsvaga zvinyorwa zvako zvichibva pane zvakatemwa. Semuenzaniso, kana iwe ukapinda zip code, database inotarisira kuwana nhamba shanu, kana kuti yek zip code yakakwana US: nhamba shanu dzinoteverwa ne hyphen, uye dzimwe nhamba ina. Kana iwe ukaisa zita rako mu zip code field, database inogona kunyunyuta.
Izvozvo ndezvokuti dhesiyo iri kuedza kuvhara kwako kunopesana nechirongwa chakatsanangurwa ye zip code field. Inzvimbo inonyanya kushandiswa kwemashoko iyo inogona kusanganisira zvipingamupinyi zvaunogona kuita.
Kunzwisisa Database Domain
Kuti tinzwisise nzvimbo yekuchengetedzwa kwemashoko, regai tione zvimwe zvishoma zvepa database:
- A database sedma rinotsanangura seti yezvimiti , inonziwo mapuranga kana masimi. Semuenzaniso, kana iwe uine tafura "Mashoko Ekubatsira Kwavashandi," inogona kusanganisira maitiro ekutangaName, LastName, JobTitle, StreetAddress, City, State, ZipCode, PhoneNumber uye Imeyili.
- Chimwe nechimwe chine chinzvimbo chinorondedzera maringe. Izvi zvinogona kusanganisira rudzi rwekutsvaga, urefu, maitiro uye mamwe mashoko.
Semuenzaniso, nzvimbo yeZivCode inogona kujekesa nhamba yemhando yedunhu, yakadai sewe integer, inowanzonzi INT kana INTEGER, zvichienderana ne database. Kana kuti wekugadzirisa magwaro angasarudza kuzvitsanangura pane chimiro, kazhinji chinonzi CHAR. Chirevo chacho chinogona kuwedzerwa kutsanangurwa kunoda urefu hwakareba, kana kuti chinhu chisina chinhu kana chisingazivikanwi chinotenderwa.
Paunounganidza zvinhu zvose zvinotsanangura nzvimbo, unoguma nemhando yakasiyana-siyana yemhando, inonziwo "user-defined data type" kana UDT.
Nezve Domain Integrity
Izvo zvinobvumirwa maitiro ehutano zvinogadzira chiremera chekutendeka , izvo zvinovimbisa kuti data yose iri mumunda ine maitiro anokosha.
Dzimba dzakatendeseka dzinotsanangurwa ne:
- Nhamba ye data, yakadai senhare, unhu kana decimal
- Iyo yakabvumira urefu hwe data
- Rwendo, kurondedzera miganhu yepamusoro uye yakaderera
- Chero zvipingamupinyi , kana zvikanganiso pane zvigamuchirwa. Semuenzaniso, imwe zipikisi ye US zip code inogona kusimbisa kukwana ZIP + 4 code , kana kuti yakazara nhamba yepfini.
- Rudzi rwekutsigira kweNULL, kana kuti chiitiko chinogona kunge chisina kuzivikanwa, kana kuti NULL kukosha
- Iko kusina kukosha, kana pane
- Zuva racho, kana zvichibvira (somuenzaniso, dd / mm / yy kana mm / dd / yyyy)
Kuumba Domain
Kune databases dzinoshandisa SQL (Yakagadziriswa Mutauro Mutauro) kana tambo yeSQL, shandisa murairo we CREATE DOMAIN SQL.
Semuenzaniso, mutemo wekuuraya pano unogadzira ZipCode chimiro che data data CHAR nemhando shanu. A NULL, kana kuti isingazivikanwi, haibvumirwi. Nhamba ye data inofanira kuwira pakati pe "00000" ne "99999." inogadzira ZipCode chimiro che data data CHAR nemhando shanu. A NULL, kana kuti isingazivikanwi, haibvumirwi. Nhamba ye data inofanira kuwira pakati pe "00000" ne "99999."
DZENGA DOMAIN ZipCode CHAR (5) HERE NULL CHECK (VALUE> '00000' AND VALUE
Rudzi rwemhando yega yega yega inopa nzira yekutsanangurira zvigadziriswa nemitemo iyo inotonga data inogamuchirwa, kunyange kana isingaiti iyo nzvimbo. Ona zvinyorwa zvepa database yako zvemashoko.