ʻO ke kūlana hana kūlana piha kahi hoʻonohonoho kūnaewele i kūlike e like me ke kūlana normalization o ke Formal Normal (2NF) . I loko o ka pōkole, eia keʻano e kū ana i nā koi o ka Nānā Mua Nūhou (1NF), aʻo nā pono kīnāʻole a pau e pili pono ana i ka kī nui.
ʻAʻohe paʻakikī kēia me he mea kani paha. E nānā kākou i kēia ma nā kiko kiko'ī.
Ka Palena o ka Pepa Nānā mua
Ma mua o ka hikiʻana i ke kikowaena ke kū pono i ka hana, pono ia e kū mua i ka Pelekane Nānā mua .
ʻO kēia a pau,ʻo kēlā me kēiaʻokoʻa e paʻa i kahi helu hoʻokahi.
Eia kekahi laʻana, ʻaʻole e pili kēia table i ka 1NF, no ka mea, ua pili ka limahana o Tina i nā wahiʻelua,ʻo lāuaʻelua i loko o ke kele hoʻokahi;
Ka Limahana | Kahi |
---|---|
ʻO Ioane | ʻo Los Angeles |
ʻO Tina | Los Angeles, Chicago |
ʻO ka hoʻokuʻuʻana i kēia hoʻolālāʻana e hiki ke hana kūponoʻole i nā hōʻailonaʻikepili a i nā mea kākau. No ka hōʻoiaʻana i ka 1NF, hoʻololi i ka papa i hiki i nā'aiamo a pau (aiʻole nā pūnaewele kolo) e paʻa i kahi helu hoʻokahi:
Ka Limahana | Kahi |
---|---|
ʻO Ioane | ʻo Los Angeles |
ʻO Tina | ʻo Los Angeles |
ʻO Tina | ʻO Chicago |
Akā,ʻaʻole i lawa ka 1NF e pale i nā pilikia me kaʻikepili.
Peheaʻo 2NF e hana ai e hōʻoiaʻiʻo i ke kūlana piha
No ka hilinaʻi piha loa, pono nā hiʻonaʻokoʻa o ka māheleʻole ma ka kī nui. (E hoʻomanaʻo, he kī liʻiliʻi o ka moena ke kiʻina (he laʻana, he kī nui a iʻole keʻano'ē paha) i hoʻohanaʻia no kaʻikeʻana i kaʻikepili pūnaewele.
Hoʻolālā nā mea hoʻolālā i kaʻikepili no ka weheweheʻana i nā pilina pili i waena o nāʻano:
Inā hoʻoholo ke koho i ka waiwai o B, kākau mākou i kēia A -> B -ʻo ia hoʻi, pili ponoʻo B ma luna o A. Ma kēia pilina,ʻo A ka mea e hoʻoholo ai i ka waiwai o B, aʻo B e pili ana iā A.
No ka laʻana, i loko o ka papahana ma lalo o ka ' Oihana ,ʻO EmployeeID a me DeptID nā kī pāʻoihana:ʻO ka EmployeeID ke kī nui o ka papa aʻo DeptID he kī'ē.
ʻO kekahi mea'ē aʻe - ma kēia hihia, EmployeeName a DeptName - pono ke hilinaʻi ma ka kī nui e loaʻa ai kona waiwai.
EmployeeID | HanaName | DeptID | DeptName |
---|---|---|---|
Emp1 | ʻO Ioane | Dept001 | ʻO ke kālā |
Emp2 | ʻO Tina | Dept003 | Nā kūʻai |
Emp3 | ʻO Carlos | Dept001 | ʻO ke kālā |
Ma kēia hihia,ʻaʻole ka manaʻo piha loa o ka papa no ka mea, oiaiʻo ka EmployeeName e pili ana i ka mea hoʻohana nui Key,ʻo DeptName ka mea i hoʻololi ma luna o ka DeptID. ʻO kēia ke kapaʻia heʻano hilinaʻiʻole .
No ka hoʻokōʻana i kēia papa e like me 2NF, pono mākou e hoʻokaʻawale i nāʻikepili i nā papaʻelua:
EmployeeID | HanaName | DeptID |
---|---|---|
Emp1 | ʻO Ioane | Dept001 |
Emp2 | ʻO Tina | Dept003 |
Emp3 | ʻO Carlos | Dept001 |
Wehe mākou i ka inoa DeptName mai ka papahana limahana a me ka hoʻokumuʻana i kahi papaʻaina Papahana :
DeptID | DeptName |
---|---|
Dept001 | ʻO ke kālā |
Dept002 | Nā Kānaka Hana |
Dept003 | Nā kūʻai |
I kēia manawa, pono loa ka pilina ma waena o nā papaʻaina, aiʻole ma 2NF.
He mea nui ke kālele
Hiki i ka hilinaʻi piha i nāʻikepiliʻikepili ke kōkua i ka hōʻoia ponoʻana o kaʻikepili a pale i nā anomalies data
Kekahi laʻana, e noʻonoʻo i ka papa i ka mahele o luna nei i kahi wale nō a 1NF. Eia hou, eia hou:
Ka Limahana | Kahi |
---|---|
ʻO Ioane | ʻo Los Angeles |
ʻO Tina | ʻo Los Angeles |
ʻO Tina | ʻO Chicago |
Aia iā Tinaʻelua mau moʻolelo. Inā mākou e hōʻoia i kahi me ka maopopoʻole heʻelua,ʻo ka hopena, heʻikeʻole ia.
A iʻole, inā makemake mākou e hoʻonui i kahi limahana i kēia pākaukau, akā,ʻaʻole mākou iʻike i kēia wahi? Hiki paha iā mākou ke hōʻole i ka hoʻokomo houʻana i kekahi limahana hou ināʻaeʻole ke kuleana'āina i nā koina NULL.
ʻAʻole pono ka hilinaʻi piha i ke kiʻi holoʻokoʻa, akā, ke pili i ka hoʻolālā. Ponoʻoe e hōʻoia i kāu kikowaena iʻekolu puka kūikawā (3NF).