Determinants inoratidza hutano hwakapiwa kune dzimwe humwe unhu
Chinhu chinogadziriswa mufurafura yepa database ndechimwe chinhu chinogona kushandiswa kugadzirisa maitiro anopiwa kune dzimwe humwe mutsara mumutsara mumwe chete. Neyi tsanangudzo, chero chinhu chikuru chinonyanya kukosha kana chikwata chekutsvaga chiyeuchidzo, asi pane zvingave zvinogadzirisa izvo zvisingasviki kana kuti zvigadziriswa.
Somuenzaniso, kambani inogona kushandisa tafura nemafungiro , , uye .
| Employee_id | Zita rokutanga | Zita rokupedzisira | Zuva rekuzvarwa |
|---|
123
| Megan | Bhurawuni | 01/29/1979 |
| 234 | Ben | Wilder | 02/14/1985 |
| 345 | Megan | Chowdery | 2/14/1985 |
| 456 | Charles | Bhurawuni | 07/19/1984 |
Muchiitiko ichi, munda inogadzirisa masasa matatu akasara. Zita reminda haritauri kuti nokuti firm inogona kuva nevashandi vanogovera rimwechete rokutanga kana rekupedzisira. Saizvozvowo, iyo masimi haasarudze kana kuti mazita mazita nokuti vashandi vanogona kugovera zuva rimwechete rekuberekwa.
Determinant Relationships to Database Keys
Mumuenzaniso uyu, inogadzirisa, chinhu chakakosha, uyewo chinhu chikuru. Icho chinhu chakakosha nokuti kana database yose iri kutsvaga 234, mutsara waiva nemashoko pamusoro paBen Wilder unooneka uye hapana rimwe rekodhi rinoratidzwa. Chimwe chinyorwa chinokosha chinoitika kana iwe uchitsvaga dhesiyo nemashoko ari mumatatu matatu; , uye , iyo inowana zvakare mhinduro imwe chete.
Iko ndiyo inokosha yepamusoro nekuda kwezvose zvakasanganiswa zvemasumeri zvinogona kushandiswa sechinhu chakakosha, ndicho chinyorwa chiri nyore kuti chishandise sechinyanya kutaurwa petafura iyi.
Uyezve, inopihwa kuti yakasiyana neyetafura ino, zvisinei kuti vangani vashandi varipo, kusiyana nemashoko mune mamwe ma column.