Ndeyeukama Database. Pfungwa ndeyeukama Database

The kwaita zvigadzirwa kombiyuta mashoko edu ano akacherekedza kumukira munyaya zvose mabasa evanhu. Asi kune vose mashoko hauzoti zvisingakoshi dongo paIndaneti, yakanga yakagadzirwa pakati Database hurongwa, umo zvinhu zviri arongwe, systematized, zvokuti vari nyore kuwana uye vanozviisa pasi haizopereri kugadzira. Pane huru akasiyana matatu - govera Database ndeyeukama, hierarchical, nomumbure.

kosha Modèles

Vodzokera kwaita Databases, zvinofanira kutaurwa kuti izvi zvakanga zvisinganyanyi kunzwisisa, izvozvo zvinobva kukura ane programmable mashoko kugadzira michina. Hazvishamisi kuti nhamba mienzaniso pari inosvika zvinopfuura 50, asi zvikuru vari kuonekwa hierarchical, ndeyeukama uye network, iro richiri kushandiswa chaizvo tsika. Chii chavanoita vanomirira?

Hierarchical Database ane muti marongerwo uye rinoumbwa nemashoko akasiyana siyana pakati paine kutaurirana. Network Database womuenzaniso uri muenzaniso kupfuura kuoma. maumbirwo awo chakafanana akanyatsorongwa, uye vanoronga kuwedzerwa uye akavandudzika. Musiyano pakati pavo kuti nhaka hierarchical mashoko mienzaniso inogona chokuita tateguru mumwe chete, ukuwo mambure kungava zvinoverengeka. Sechivako ndeyeukama Database zvakawanda kunzwisisa. Saka, tinofanira namambo mumwe chete dzakaparara zvizere.

The pfungwa imwe ndeyeukama Database

muenzaniso uyu mune 1970 naDr Edgar F. Codd sayenzi. Chinhu zvine musoro muronga tafura minda kuti kundorondedzera data, avo ukama nemumwe, akavhiyiwa anoitwa pamusoro pavo, uye Chikurukuru - mitemo hunovimbisa kuvimbika kwavo. Nei anonzi ndeyeukama muenzaniso? Zvinonzi inobva ukama (kubva muchiLatin. Relatio) pakati mashoko. Kune tsanangudzo dzakawanda ichi mhando Database. Ndeyeukama matafura nemashoko ari nyore zvikuru kuronga kupa kurapwa, pane zvakarukwa kana hierarchical womuenzaniso. sei kuzviita? Zvaringana kuziva features, muenzaniso mamiriro uye zvivako zviri ndeyeukama pamatafura.

Pfungwa Modelling uye zvinokosha

Kuti pave yako Database, unofanira kushandisa imwe Modelling nematurusi vanofungei chii mashoko unofanira kushanda, kuti vagoronga ndeyeukama tafura uye kuroorwa uye akawanda Links pakati Data masangano kuti kuzadza muchitokisi uye akaisa chikuru kana dzimwe kiyi.

Modelling matafura uye afunge ndeyeukama Databases rinoitwa kuburikidza vakasununguka zvishandiso akafanana Workbench, PhpMyAdmin, Case Studio, dbForge Studio. Pashure hwakadzama pamasikiro kuzoponesa kwakajeka zvikapera ndeyeukama muenzaniso uye kurishandura kuva SQL-vakagadzirira romutemo. Panguva iyi, unogona kutanga kushanda pamwe Data Sorting, kubudiswa uye systematization.

Zvakakurukurwa marongerwo uye mashoko chokuita hukama womuenzaniso

mabviro neimwe yazvo nenzira rinotsanangura zvinhu zvayo, saka ndinoda kupa zvishoma runyerekupe pamusoro shoma kuvhiringidzika:

• ndeyeukama chitaridzi = hunhu;
• marongerwo = vanoti zita = gorofu = Mbiru Header sangano;
• sangano Somuenzaniso = tuple = rekodhi = ndiro mutsetse;
• chizenga = ukoshi = sero masangano munda.

Kuenda ndeyeukama Database ehupfumi vanofanira kungwarira vamwe inokosha nayo unotora zvinoriumba uye zvavanotsvakira kurehwa.

1. Chaizvoizvo. Table ndeyeukama Database kunogona chete, kana angava akaita matafura zvinoumba zvinorondedzerwa zvinhu zvakachengetwa imomo pachishandiswa mashoko. Vane wakaiswa nhamba yeminda, uye shanduka uwandu vakanyoresa. Table ndeyeukama womuenzaniso Database rinoumbwa hungiso, hunhu, uye marongerwo.
2. Kutsikisa - a shanduka nhamba mitsara kuti kuratidza umboo kuti munguva zvinorondedzerwa chinhu. Vakaverengwa Entries akaita rwoga nokuda hurongwa.
3. Anoti - Data kuratidza pfupiso pembiru.
4. Field. Zviri sangano mbiru. nhamba yavo - yakatarwa ukoshi yakaiswa pakusika kana nadzurudzo petafura.

Zvino, nokuziva constituent zvinhu patafura, unogona kufamba kusvika ehupfumi ari ndeyeukama womuenzaniso Database:

• Musimboti maviri-dimensional ndeyeukama Database. Nokuda pfuma iyi navo nyore prodelyvat siyana musoro uye akarongeka kushandiswa.
• Murayiro chizenga tsika uye zvinyorwa mune ndeyeukama tafura kunogona zvemasanga.
• Column mukati munhu ndeyeukama tafura anofanira zita yayo rakasiyana.
• Data vose mbiru chezvematongerwe vane yakamisirwa kureba uye kwakadaro.
• kupinda Chero Chaizvoizvo ichaongororwa somunhu chimedu mashoko.
• Constituent zvinoumba mechidziro nevamwe. Hukama vasiri nouya pemitsara.

Inobva ehupfumi ari ndeyeukama Database, zvinonzwisiswa kuti zvinokosheswa hunhu vanofanira kuva kwakadaro, kureba. Funga nezveimwe chizenga tsika.

The chikuru zvechadenga minda ndeyeukama Databases

mazita munda unofanira kuva akasiyana mukati chete isangano. The Mhando hunhu kana minda ndeyeukama Databases anorondedzera chikamu nemashoko zvakachengetwa muminda sangano. Field ndeyeukama Database anofanira kuva yakamisirwa saizi, iro rinowanikwa mune vatambi. Parameters uye Format chizenga tsika dzaanofanira netsika kururamisa mashoko avo. Asi pane kudaro chinhu se "chifukidzo" kana "wedzera template". Rakagadzirirwa kuona configuration ari umboo mazano ari chizenga ukoshi. Zvamazvirokwazvo panguva isiri rekodhi mhando mashoko anofanira yakapiwa kapukanana mushumo mumunda. Uyewo ari musango zvinhu dzimwe zvausingakwanisi - mamiriro kuongorora kururama uye zvakarurama kuti mashoko mukova. Pane mutemo unoti chizenga ukoshi kuti inonanga anofanira kuzadzwa mashoko. Vamwe chizenga mutsetse zadzwe null-tsika. Kupinda risina mashoko munda unhu. Zvakafanana kapukanana nomushumo, pane tsika kuti vakazadzwa rwoga parutivi hurongwa - ndiwo default Data. Kuti rikurumidze kutsvaka chero Data vaida Indexed munda.

Scheme ndeiya yakaita ndeyeukama Database tafura

Kana uchida kunzwisisa utariri hurongwa womuenzaniso uchishandisa SQL zvakanakisisa kufunga zano muenzaniso. We uchitoziva ari ndeyeukama Database. An kupinda neimwe tafura - rimwe chete mashoko Kufananidzira. Kudzivirira date redundancy, zvakakodzera kuti normalize nokushanda.

The inokosha mitemo normalization kuti hukama hunhu

1. Kukosha munda zita kuti hukama tafura anofanira kuva akasiyana, mumwe mhando (First Normal Form - 1NF).

2. Nokuti tafura wakatobatsira yaitwa 1NF, vasiri kuona zita ipi mbiru kuva novimba rakasiyana patafura identifier (2NF).

3. Nokuti matafura ose vakatobatana inochengetwa 2NF, vasiri kuona mumwe munda unogona kuva yakazvimirira nevamwe zvinowanikwa zvinosanganisira maatomu akafanana tsika (3NF sangano).

Databases: ndeyeukama Links pakati matafura

Kune 2 chikuru marudzi ukama pakati ndeyeukama mahwendefa:

• "Mumwe-zhinji". Maererano kunoitika apo mumwe anokosha tafura kupinda №1 akawanda zviitiko rechipiri sangano. Icon Key parimwe kumigumo yakavhomorwa mutsetse unoratidza kuti fuma iri kurutivi "mumwe", mumwe mugumo mutsetse kazhinji chiratidzo kusaverengeka chiratidzo.

• Kukurukurirana "vazhinji-zhinji" yakaumbwa panyaya dzakawanda misara mumwe musoro sangano yakajeka kusakarongeka ane nhamba yamashoko imwe tafura.
• Kana masangano maviri pane concatenation kuti "munhu mumwe chete", zvinoreva kuti chinokosha identifier mumwe tafura aripo mune dzimwe sangano, ipapo zvakafanira kubvisa imwe matafura, handifaniri. Asi dzimwe nguva chete kuchengeteka programmers ndeimwewo kuparadzanisa masangano maviri. Naizvozvo, zvokufungidzira, kubatana pakati "munhu mumwe" anogona kuvapo.

Kuvapo kiyi ari ndeyeukama Database

Nesekondari makiyi vangaziva zvinogona Database ukama. Ndeyeukama Data kutaurirana womuenzaniso anogona chimwe chete kukwikwidza kiyi, ichava chikuru chinokosha. Chii? Primary kiyi - wechikamu kana unhu inokosha, kuburikidza iyo unogona kuwana imwe date mutsetse. Zvinofanira kuva akasiyana, chete, uye minda yayo zvarisingagoni null tsika. Kana chikuru kiyi chinosanganisira mumwe chete chizenga, zvino anonzi nyore, zvimwe zvichaita.

Kunze chikuru kiyi, ariko uye zvokunze (wokumwe kiyi). Vakawanda havanzwisisi chii musiyano pakati pavo. Ngationgororei navo muudzame muenzaniso. Saka, pane matafura maviri: "Dean" uye "Students '. Musimboti "Dean" rine minda: ". Group" "ID mudzidzi", "Zita" uye Table "Students" ane chizenga tsika dzakadai se "Zita", "Group" uye "Average". Saka sezvinoita ID mudzidzi kwete zvinogonawo kuti vadzidzi vashoma, ndiwo munda kuva kiyi chikuru. "Zita" uye "Group" kubva "vadzidzi" petafura zvingava zvakafanana mashomanana vanhu, ivo vanotaura ID nhamba romudzidzi kubva musimboti "Dean", saka vanogona kushandiswa sezvo isiri kiyi.

Muenzaniso ndeyeukama Database muenzaniso

Kuti zvijeke, tinopa munhu muenzaniso ndeyeukama Database muenzaniso zvinosanganisira masangano maviri nyore. Pane tafura ne zita "Dean".

Zvakakosha kuita maererano kuwana zvizere hukama Database. Entry "IN-41" uyewo "IN-72", vangave kanopfuura kamwe patafura "Dean" sezvo anonziwo, zita uye patronymic nevadzidzi, muna zvisingawanzoitiki zviitiko, zvinogonawo, saka minda izvi havagoni kuva kuti chinonyanya kiyi. musimboti "Vadzidzi" acharatidza.

Sezvo tinogona kuona, mhando yeminda Database ndeyeukama anosiyana zvachose. Present sezvo digitaalinen zvakarekodhwa uye tsika. Naizvozvo, chizenga Kurongwa vanofanira kuratidza kukosha integer, vaIsakari, vachar, zuva uye nevamwe. Mu "Dean" ukoshi hwakasiyana nemamwe ndiyo chete ID mudzidzi. munda Izvi zvinogona kutorwa sechinhu kiyi chikuru. Name, yokudhirowa, uye runhare kubva musimboti "Vadzidzi" rinogona kutorwa sechinhu kiyi vatorwa tsvaga ari ID mudzidzi. The Kubatana inovhurwa. Uyu ndiwo muenzaniso aakaudzwa muenzaniso "munhu mumwe". Zvokufungidzira, mumwe zvokuwedzera matafura, vanogona kuva nyore kubatanidzwa mune rimwe sangano. Kuna ID-nhamba vadzidzi havana kuva kwose kuzivikanwa, ingangodaro kuti pane nematafura maviri.