DB - nws ... Lub hom thiab cov khoom ntawm ib tug database

DB - ib qho acronym uas stands "database" los yog "database" (nyob ntawm seb lub ntsiab lus teb). Nyob rau hauv no tsab xov xwm, peb xav tias nws / lawv, dab tsi yog thiab qhov twg mus thov. Thiab sib tham lub DBMS thiab database - nws yog tib yam los yog tsis.

terminology

Database xa mus rau tej yam kev repository ntawm cov ntaub ntawv. DB - nws tseem yog ib tug ntaub ntawv qauv, lub peev xwm kom muaj ib tug tej yam ntaub ntawv, nrog rau cov proviso hais tias lawv yuav tsum yuam kom them. Peb txhua tus tau ua hauj lwm nrog cov database tsawg kawg yog ib zaug, tab sis nws yuav tsis txawm twv ntawm, piv txwv li, los ntawm uas nkag mus rau ib tug kev tshawb fawb lub sij hawm, peb tig mus rau ib tug loj-scale lub hauv paus rau tej ntaub ntawv cov ntaub ntawv.

DBMS - yog lwm acronym, uas stands rau "database tswj system". Nyob rau hauv ib tug general kev txiav txim zoo, lawv sawv cev ib tug ntau yam ntawm software dlaws, uas koj yuav npaj lub database ntaub ntawv. Qhov no yog hais txog lub txhaws ntawm cov ntaub ntawv los luj, ordering nws, Hmong, luam, tsom xam thiab ntau npaum li cas.

Cov ntaub ntawv database

Nyob rau hauv database kev tshawb xav, muaj ob peb hom ntawm lawv. muaj:

• Paub databases (los ntawm cov lus Askiv lo lus piv, uas translates li "kev twb kev txuas") - yog yus muaj los ntawm kev sib raug zoo thiab qhia ib txheej ntawm sib xyaw chaw. Cov yav tas yog hais nyob rau hauv daim ntawv ntawm cov ntsiav tshuaj, uas muaj cov database cov ntaub ntawv. Qhov no yog feem ntau hom database.
• Xaab siab - vim mus rau theem ntawm "niam txiv-me nyuam", "superior-subordinate".
• Network - ib tug offshoot ntawm yav tas los lub hom.
• Nruas-taw qhia kom paub, uas ua hauj lwm ncaj nraim nrog cov uas tsim nyog programming vib this (PLO).

Cia peb xav txog txhua yam uas lawv nyob rau hauv kom meej, siv ceev xwmphem raws txoj kev mus rau lub yooj yim lub tswv yim thiab tswv yim ntawm ib tug database.

DB - nws yog ib tug kos npe rau?

Paub databases yog nyob rau hauv lawv li ib txwm sawv cev tsis ua teeb meem rau kev nkag siab - ib tug quav hniav uas muaj ntaub ntawv. Yuav kom paub meej, koj muaj peev xwm hu rau txoj kev pab no zoo heev paub database ntawm tuam txhab uas muag "Microsoft" - "acces", ib feem ntawm lawv ib txwm chaw ua hauj lwm daim ntaub ntawv pob.

Nyob rau hauv paub database ntxhuav muaj nkag (kab) thiab teb (kab). Tus thawj muaj cov lus qhia tam sim ntawd, cov ntaub ntawv nyob rau hauv lub dhau los lawm - ib tug piav qhia txog dab tsi nws txhais tau hais cov ntaubntawv povthawj siv. Piv txwv li, lub teb - "lub npe" nkag - "Catherine".

Rau teb txhais nqi hom. Tej zaum lawv yuav numeric, cim, hnub tim, lub sij hawm, thiab lwm yam tas li ntawd, txhua lub rooj muaj yuav ib tug tseem ceeb teb - .. Cov ntaub ntawv nyob rau ntawd uniquely qhia cov ntaub ntawv.

Nws yuav tsum tau to taub hais tias lub database nws tus kheej - nws tsis yog ib lub rooj. Lub database yuav tsum muab cia los ntawm ib tug mus rau ob peb puas ntxhuav, nyob ntawm seb tus nqi thiab muaj ntau haiv neeg ntawm cov ntaub ntawv.

Kev sib raug zoo ntawm cov ntxhuav

Yuav ua kom kev sib raug zoo ntawm cov ntxhuav nyob rau hauv cov database muaj ib tug schema. Communications yog:

• "Ib tug-rau-ib tug" - txhua cov ntaub ntawv nyob rau hauv lub rooj hnov tsuas yog ib cov ntaub ntawv los ntawm lwm lub phaj.
• "Ib tug-rau-ntau" thiab "ntau-mus-muaj coob". Cov ntaub ntawv tej zaum yuav sib haum mus rau ob peb ntawm cov uas muaj feem rooj. Xwb (thib ob embodiment).
• "Muaj ntau-mus-muaj coob." Nws tsis yog nyuaj rau twv hais tias nyob rau hauv cov ntaub ntawv no, ntau yam kab yuav tau xaiv mus cuag ntau yam kab ntawm lwm lub rooj (xws li ib tug link yog lub koom haum siv ib staging rooj thiab ob mus saum toj no hom).

Tsiv thiab nce thiab nqis

Xaab siab database muaj ntau ntau kev tshaj paub. Lawv yuav nruj kev mloog lus. Muaj yog lub hauv paus keeb - lub "ntsis", uas ceg tawm subordinates - "qub txeeg qub teg" los yog "xeeb leej xeeb ntxwv". Xaab siab database - ib lub hauv paus muaj ib tsob ntoo cov qauv nyob rau hauv uas tsuas yog ib qho txwv zeej txwv koob tej zaum yuav nyob rau txhua node.

Qhov no hom yog yooj yim siv rau lub tsev repositories ntawm cov ntaub ntawv twb tau txiav txim kom qauv: piv txwv li, lub hauv paus ua tub rog unit los yog cov ntaub ntawv saib xyuas cov ntaub ntawv. Lub disadvantage yog suav tias yog tsis yooj yim sua rau lub tsev kom muaj ntau tshaj li ib tug niam txiv, raws li zoo raws li lub complexity ntawm lub database logic.

nthuav kev sib raug zoo

Network DB steel kev txiav txim siab tsis muaj hierarchical npe cia li saum toj no. 'Muaj ntau-mus-muaj coob "Qhov tsuas sib txawv ntawm no hom ntawm yav dhau los kev sib raug zoo los ua, uas nyob rau hauv cov ntaub ntawv no yog qhia nyob rau hauv lub fact tias raws li cov txwv zeej txwv koob tej zaum yuav muaj ntau yam qub txeeg qub teg, thiab lawv, xeeb leej xeeb ntxwv, yuav tshwm sim tau los ntawm ntau o.

Tabular zaub txoj kev

Txawm tias muaj tseeb hais tias cov ntxhuav yog txuam feem nrog paub databases thiab hierarchical, network, thiab muaj peev xwm kuj yuav sawv cev nyob rau hauv daim ntawv ntawm lub rooj. Cov yooj yim sib txawv nruab nrab ntawm cov hom - nyob rau hauv hauv paus ntsiab lus hauv kev tsim kho ntawm cov qauv: paub, piv nrog rau lwm cov ob yog npaum li cas freer thiab tsawg kom.

Nruas oriented style

Xeem saib hom - ib tug kwv-taw qhia kom paub - qhov tsawg heev. Qhov no yog vim hais tias nws yog heev tshwj xeeb. Complex ntaub ntawv lug xws puag daim ntawv kwv thiab ua hauj lwm ncaj nraim nrog cov lus ntawm yam khoom-taw qhia kom paub programming. Lawv tsim nyob rau hauv lub eighties ntawm lub xyoo pua xeem thiab tsis tau txais ntau npaum li cas tej chaw vim hais tias ntawm nws cov complexity thiab tsis heev npaum li cas ntawm kev ceev.