{"id":6102,"date":"2023-08-25T00:00:00","date_gmt":"2023-08-25T00:00:00","guid":{"rendered":"https:\/\/tech-lib.eu\/tech\/jak-normalizovat-databazi-pruvodce-efektivni-organizaci-dat\/"},"modified":"2023-08-25T00:00:00","modified_gmt":"2023-08-25T00:00:00","slug":"jak-normalizovat-databazi-pruvodce-efektivni-organizaci-dat","status":"publish","type":"post","link":"https:\/\/tech-lib.eu\/tech\/jak-normalizovat-databazi-pruvodce-efektivni-organizaci-dat\/","title":{"rendered":"Jak normalizovat datab\u00e1zi. Pr\u016fvodce efektivn\u00ed organizac\u00ed dat"},"content":{"rendered":"
P\u0159edstavte se: Normalizace m\u00e1 z\u00e1sadn\u00ed v\u00fdznam pro dosa\u017een\u00ed efektivity, \u0161k\u00e1lovatelnosti a integrity dat v oblasti architektury datab\u00e1z\u00ed. Datab\u00e1zi m\u016f\u017eete uspo\u0159\u00e1dat zp\u016fsobem, kter\u00fd eliminuje redundanci a maximalizuje efektivitu, dodr\u017eov\u00e1n\u00edm souboru z\u00e1sad a doporu\u010den\u00ed. C\u00edlem t\u00e9to eseje je poskytnout \u010dten\u00e1\u0159\u016fm d\u016fkladnou p\u0159edstavu o normalizaci datab\u00e1z\u00ed, v\u010detn\u011b jej\u00ed funkce, r\u016fzn\u00fdch typ\u016f a r\u016fzn\u00fdch f\u00e1z\u00ed. Co znamen\u00e1 normalizace dat v datab\u00e1zi? Praxe uspo\u0159\u00e1d\u00e1n\u00ed datab\u00e1ze s c\u00edlem zbavit ji z\u00e1vislost\u00ed a nadbyte\u010dn\u00fdch dat se naz\u00fdv\u00e1 normalizace. Redundance je ozna\u010den\u00ed pro opakov\u00e1n\u00ed dat, kter\u00e1 nejsou nezbytn\u00e1 a mohou v\u00e9st k nep\u0159esnostem a neefektivit\u011b. Probl\u00e9my se z\u00e1vislostmi mohou nastat, kdy\u017e jedna \u010d\u00e1st dat z\u00e1vis\u00ed na jin\u00e9, co\u017e m\u016f\u017ee v\u00e9st k abnormalit\u00e1m v datech. Datab\u00e1ze je normalizov\u00e1na, kdy\u017e jsou data rozd\u011blena do men\u0161\u00edch, sn\u00e1ze spravovateln\u00fdch tabulek, \u010d\u00edm\u017e je zaji\u0161t\u011bno, \u017ee ka\u017ed\u00e1 tabulka pln\u00ed specifickou funkci a odstra\u0148uj\u00ed se probl\u00e9my s nadbyte\u010dnost\u00ed a z\u00e1vislostmi. Pot\u0159ebuje moje datab\u00e1ze normalizaci? A\u010dkoli normalizace nen\u00ed v\u017edy nutn\u00e1 pro ka\u017edou datab\u00e1zi, ve v\u011bt\u0161in\u011b situac\u00ed se d\u016frazn\u011b doporu\u010duje. Mezi mnoh\u00e9 v\u00fdhody normalizace pat\u0159\u00ed zv\u00fd\u0161en\u00e1 integrita dat, p\u0159izp\u016fsobivost a \u0161k\u00e1lovatelnost. Nebezpe\u010d\u00ed nekonzistence lze sn\u00ed\u017eit t\u00edm, \u017ee se zajist\u00ed, aby ka\u017ed\u00fd kus dat byl ulo\u017een pouze na jednom m\u00edst\u011b, \u010d\u00edm\u017e se sn\u00ed\u017e\u00ed redundance. Normalizace nav\u00edc usnad\u0148uje aktualizaci a \u00fapravy datab\u00e1z\u00ed, proto\u017ee zm\u011bny proveden\u00e9 v jedn\u00e9 tabulce nemus\u00ed nutn\u011b ovlivnit ostatn\u00ed tabulky. Normalizace nakonec zvy\u0161uje efektivitu a v\u00fdkonnost datab\u00e1ze. <\/p>\n
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Normalizace datab\u00e1ze: \u010cty\u0159i typy: B\u011b\u017en\u00e9 jsou normovan\u00e9 formy, kter\u00e9 maj\u00ed r\u016fzn\u00e9 \u00farovn\u011b normalizace. Prvn\u00ed, druh\u00e1 a t\u0159et\u00ed norm\u00e1ln\u00ed forma (1NF, 2NF a 3NF) jsou nejtypi\u010dt\u011bj\u0161\u00ed a nej\u010dast\u011bji pou\u017e\u00edvan\u00e9. Zv\u00fd\u0161en\u00e1 m\u00edra normalizace je implikov\u00e1na vy\u0161\u0161\u00ed norm\u00e1ln\u00ed formou. <\/p>\n

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1. Prvn\u00ed norm\u00e1ln\u00ed forma (1NF): V t\u00e9to form\u011b jsou data uspo\u0159\u00e1d\u00e1na do tabulek s atomick\u00fdmi hodnotami – jedna hodnota na bu\u0148ku v ka\u017ed\u00e9m sloupci. Pro ka\u017edou tabulku je nav\u00edc vy\u017eadov\u00e1n prim\u00e1rn\u00ed kl\u00ed\u010d, typ jedine\u010dn\u00e9ho identifik\u00e1toru. <\/p>\n

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2. Druh\u00e1 norm\u00e1ln\u00ed forma (2NF): Odstran\u011bn\u00edm d\u00edl\u010d\u00edch z\u00e1vislost\u00ed 2NF vylep\u0161uje 1NF. Pokud je sloupec, kter\u00fd nen\u00ed kl\u00ed\u010dem, z\u00e1visl\u00fd pouze na \u010d\u00e1sti prim\u00e1rn\u00edho kl\u00ed\u010de, jedn\u00e1 se o tzv. \u010d\u00e1ste\u010dnou z\u00e1vislost. Abyste dos\u00e1hli 2NF, mus\u00edte tyto z\u00e1vislosti odstranit rozd\u011blen\u00edm tabulky na c\u00edlen\u011bj\u0161\u00ed, men\u0161\u00ed tabulky. <\/p>\n

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T\u0159et\u00ed norm\u00e1ln\u00ed forma (3NF): Odstran\u011bn\u00edm tranzitivn\u00edch z\u00e1vislost\u00ed jde 3NF je\u0161t\u011b o krok d\u00e1le. Nekl\u00ed\u010dov\u00fd sloupec se st\u00e1v\u00e1 tranzitivn\u011b z\u00e1visl\u00fdm na jin\u00e9m nekl\u00ed\u010dov\u00e9m sloupci. Abyste dos\u00e1hli 3NF, mus\u00edte tabulku rozd\u011blit na r\u016fzn\u00e9 tabulky a zajistit, aby ka\u017ed\u00fd sloupec z\u00e1visel pouze na prim\u00e1rn\u00edm kl\u00ed\u010di. T\u0159i f\u00e1ze normalizace jsou n\u00e1sleduj\u00edc\u00ed: P\u0159i normalizaci se b\u011b\u017en\u011b prov\u00e1d\u011bj\u00ed t\u0159i kroky ozna\u010dovan\u00e9 jako t\u0159i norm\u00e1ln\u00ed formy. <\/p>\n

1. Prvn\u00ed norm\u00e1ln\u00ed forma (1NF): V tomto bod\u011b je t\u0159eba zajistit, aby ka\u017ed\u00e1 tabulka m\u011bla prim\u00e1rn\u00ed kl\u00ed\u010d a aby ka\u017ed\u00fd sloupec m\u011bl atomick\u00e9 hodnoty. <\/div>\n

2. Druh\u00e1 norm\u00e1ln\u00ed forma (2NF): D\u00edky rozd\u011blen\u00ed tabulky na men\u0161\u00ed tabulky v\u00e1m tato f\u00e1ze umo\u017en\u00ed zbavit se v\u0161ech d\u00edl\u010d\u00edch z\u00e1vislost\u00ed. <\/p>\n

3. T\u0159et\u00ed norm\u00e1ln\u00ed forma (3NF): V posledn\u00edm kroku se dal\u0161\u00edm rozd\u011blen\u00edm tabulek odstran\u00ed tranzitivn\u00ed z\u00e1vislosti. <\/div>\n

Je d\u016fle\u017eit\u00e9 poznamenat, \u017ee normalizace nad r\u00e1mec t\u0159et\u00ed norm\u00e1ln\u00ed formy (neboli 3NF), nap\u0159\u00edklad \u010dtvrt\u00e1 norm\u00e1ln\u00ed forma (neboli 4NF), se vyu\u017e\u00edv\u00e1 m\u00e9n\u011b \u010dasto a z\u00e1vis\u00ed na jedine\u010dn\u00fdch po\u017eadavc\u00edch a slo\u017eitosti datab\u00e1ze. <\/p>\n

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Shrnut\u00ed: <\/p>\n

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D\u016fle\u017eit\u00fdm krokem k vytvo\u0159en\u00ed funk\u010dn\u00ed a dob\u0159e uspo\u0159\u00e1dan\u00e9 struktury dat je normalizace datab\u00e1ze. Normalizace umo\u017e\u0148uje odstranit probl\u00e9my s duplicitou a z\u00e1vislostmi, zajistit integritu dat a zv\u00fd\u0161it v\u00fdkon. Aby bylo zaji\u0161t\u011bno, \u017ee ka\u017ed\u00e1 tabulka bude m\u00edt odli\u0161nou funkci, a aby se omezily anom\u00e1lie v datech, nab\u00edzej\u00ed t\u0159i norm\u00e1ln\u00ed formy (1NF, 2NF a 3NF) systematickou metodu normalizace. U v\u011bt\u0161iny datab\u00e1z\u00ed se normalizace vyplat\u00ed i p\u0159es po\u010d\u00e1te\u010dn\u00ed \u00fasil\u00ed, kter\u00e9 m\u016f\u017ee vy\u017eadovat.<\/p><\/div>\n

\n
FAQ<\/div>\n
\n
Co je to 1. 2. a 3. normalizace?<\/div>\n

Prvn\u00ed, druh\u00e1 a t\u0159et\u00ed norm\u00e1ln\u00ed forma slou\u017e\u00ed jako n\u00e1vrhy uspo\u0159\u00e1d\u00e1n\u00ed dat v rela\u010dn\u00ed datab\u00e1zi zp\u016fsobem, kter\u00fd minimalizuje duplicitu dat a zvy\u0161uje jejich integritu. Zde je jejich stru\u010dn\u00fd p\u0159ehled: <\/p>\n

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1. Prvn\u00ed norm\u00e1ln\u00ed forma (1NF): V 1NF jsou data uspo\u0159\u00e1d\u00e1na do tabulek s \u0159\u00e1dky a sloupci a v ka\u017ed\u00e9m sloupci jsou p\u0159\u00edtomny pouze atomick\u00e9 hodnoty (ned\u011bliteln\u00e9 hodnoty). Tabulka by nem\u011bla obsahovat \u017e\u00e1dn\u00e9 opakuj\u00edc\u00ed se skupiny nebo pole. Tato forma zaru\u010duje, \u017ee ka\u017ed\u00e1 hodnota ve sloupci je odli\u0161n\u00e1 a \u017ee ka\u017ed\u00fd \u0159\u00e1dek m\u00e1 prim\u00e1rn\u00ed kl\u00ed\u010d, kter\u00fd jej jednozna\u010dn\u011b identifikuje. <\/p>\n

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2. Druh\u00e1 norm\u00e1ln\u00ed forma (2NF): V 2NF jsou v\u0161echny nekl\u00ed\u010dov\u00e9 charakteristiky funk\u010dn\u011b z\u00e1visl\u00e9 na pln\u00e9m prim\u00e1rn\u00edm kl\u00ed\u010di a tabulka je ji\u017e v 1NF. To znamen\u00e1, \u017ee z\u00e1kladem ka\u017ed\u00e9ho sloupce v tabulce by m\u011bl b\u00fdt \u00fapln\u00fd prim\u00e1rn\u00ed kl\u00ed\u010d, a ne jen jeho \u010d\u00e1st. Nekl\u00ed\u010dov\u00fd atribut by m\u011bl b\u00fdt p\u0159eveden do jin\u00e9 tabulky, pokud na prim\u00e1rn\u00edm kl\u00ed\u010di z\u00e1vis\u00ed jen \u010d\u00e1ste\u010dn\u011b. <\/p>\n

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3. T\u0159et\u00ed norm\u00e1ln\u00ed forma (3NF): Ve 3NF by nem\u011bly existovat \u017e\u00e1dn\u00e9 tranzitivn\u00ed vazby mezi nekl\u00ed\u010dov\u00fdmi atributy, proto\u017ee tabulka je ji\u017e ve 2NF. To znamen\u00e1, \u017ee nekl\u00ed\u010dov\u00fd atribut by m\u011bl b\u00fdt p\u0159enesen do jin\u00e9 tabulky, pokud z\u00e1vis\u00ed na jin\u00e9m nekl\u00ed\u010dov\u00e9m atributu. Ve\u0161ker\u00e9 nep\u0159\u00edm\u00e9 vazby mezi nekl\u00ed\u010dov\u00fdmi atributy je t\u0159eba odstranit. <\/p>\n

<\/div>\n

Tyto normaliza\u010dn\u00ed formy lze pou\u017e\u00edt k efektivn\u00edmu strukturov\u00e1n\u00ed datab\u00e1z\u00ed, zaru\u010den\u00ed konzistence dat, zbaven\u00ed se duplicitn\u00edch dat a usnadn\u011bn\u00ed manipulace s daty a jejich \u00fadr\u017eby. <\/p>\n<\/div>\n

\n
Jak normalizovat data v jazyce SQL?<\/div>\n

Pro normalizaci dat v jazyce SQL m\u016f\u017eete dodr\u017eovat soubor pravidel ozna\u010dovan\u00fdch jako normaliza\u010dn\u00ed formy datab\u00e1ze. N\u00e1sleduj\u00edc\u00ed formy jsou nejtypi\u010dt\u011bj\u0161\u00ed: <\/p>\n

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1. Prvn\u00ed norm\u00e1ln\u00ed forma (1NF): Zajist\u011bte, aby tabulka obsahovala pouze atomick\u00e9 hodnoty a aby v \u017e\u00e1dn\u00e9m z jej\u00edch sloupc\u016f neexistovaly opakuj\u00edc\u00ed se skupiny dat. <\/p>\n

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2. Druh\u00e1 norm\u00e1ln\u00ed forma (2NF): Zajist\u011bte, aby ka\u017ed\u00fd sloupec, kter\u00fd nen\u00ed kl\u00ed\u010dem, pln\u011b z\u00e1visel na prim\u00e1rn\u00edm kl\u00ed\u010di tabulky a z\u00e1rove\u0148 spl\u0148oval po\u017eadavky 1NF. <\/p>\n

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3. T\u0159et\u00ed norm\u00e1ln\u00ed forma (3NF): Krom\u011b spln\u011bn\u00ed 2NF se ujist\u011bte, \u017ee \u017e\u00e1dn\u00e9 nekl\u00ed\u010dov\u00e9 sloupce nejsou na sob\u011b navz\u00e1jem p\u0159echodn\u011b z\u00e1visl\u00e9. <\/p>\n

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K dosa\u017een\u00ed normalizace m\u016f\u017eete prov\u00e9st n\u00e1sleduj\u00edc\u00ed akce: <\/p>\n

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1. Ur\u010dete hlavn\u00ed entity a jejich p\u0159idru\u017een\u00e9 vlastnosti: Vypi\u0161te hlavn\u00ed entity ve va\u0161\u00ed datab\u00e1zi a jejich doprovodn\u00e9 vlastnosti. 2. Ur\u010dete prim\u00e1rn\u00ed kl\u00ed\u010de: Vyberte prim\u00e1rn\u00ed kl\u00ed\u010d pro ka\u017edou entitu, kter\u00fd ur\u010dit\u00fdm zp\u016fsobem identifikuje ka\u017edou polo\u017eku v datab\u00e1zi. <\/p>\n

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3. Zbavte se opakuj\u00edc\u00edch se skupin: Vytvo\u0159te nov\u00e9 tabulky a spojen\u00ed, abyste se zbavili v\u0161ech opakuj\u00edc\u00edch se skupin. <\/p>\n

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4. Odstra\u0148te \u010d\u00e1ste\u010dn\u00e9 z\u00e1vislosti: V p\u0159\u00edpad\u011b pot\u0159eby rozd\u011blte tabulku na v\u00edce tabulek, aby ka\u017ed\u00fd sloupec, kter\u00fd nen\u00ed kl\u00ed\u010dem, byl z\u00e1visl\u00fd na cel\u00e9m hlavn\u00edm kl\u00ed\u010di. 5. Odstra\u0148te tranzitivn\u00ed z\u00e1vislosti: Odd\u011blen\u00edm v\u0161ech nekl\u00ed\u010dov\u00fdch sloupc\u016f, kter\u00e9 jsou z\u00e1visl\u00e9 na jin\u00fdch nekl\u00ed\u010dov\u00fdch sloupc\u00edch, je odstra\u0148te. <\/p>\n

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6. Vytvo\u0159te vztahy: Pro zaji\u0161t\u011bn\u00ed referen\u010dn\u00ed integrity vytvo\u0159te spojen\u00ed mezi tabulkami pomoc\u00ed ciz\u00edch kl\u00ed\u010d\u016f. <\/p>\n

<\/div>\n

Tyto postupy a normaliza\u010dn\u00ed formul\u00e1\u0159e lze pou\u017e\u00edt k efektivn\u00edmu strukturov\u00e1n\u00ed dat v jazyce SQL.<\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

P\u0159edstavte se: Normalizace m\u00e1 z\u00e1sadn\u00ed v\u00fdznam pro dosa\u017een\u00ed efektivity, \u0161k\u00e1lovatelnosti a integrity dat v oblasti architektury datab\u00e1z\u00ed. Datab\u00e1zi m\u016f\u017eete uspo\u0159\u00e1dat zp\u016fsobem, kter\u00fd eliminuje redundanci a maximalizuje efektivitu, dodr\u017eov\u00e1n\u00edm souboru z\u00e1sad a doporu\u010den\u00ed. C\u00edlem t\u00e9to eseje je poskytnout \u010dten\u00e1\u0159\u016fm d\u016fkladnou p\u0159edstavu o normalizaci datab\u00e1z\u00ed, v\u010detn\u011b jej\u00ed funkce, r\u016fzn\u00fdch typ\u016f a r\u016fzn\u00fdch f\u00e1z\u00ed. Co znamen\u00e1 normalizace dat … \u010c\u00edst d\u00e1l<\/a><\/p>\n","protected":false},"author":923,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2447],"tags":[],"class_list":["post-6102","post","type-post","status-publish","format-standard","hentry","category-normalizace-databaze"],"_links":{"self":[{"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/posts\/6102","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/users\/923"}],"replies":[{"embeddable":true,"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/comments?post=6102"}],"version-history":[{"count":0,"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/posts\/6102\/revisions"}],"wp:attachment":[{"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/media?parent=6102"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/categories?post=6102"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tech-lib.eu\/tech\/wp-json\/wp\/v2\/tags?post=6102"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}