Ulwalamano olulodwa kunye nolunye luyingxenye ebalulekileyo yokwakha idatha
Ulwalamano olulodwa kunye nolunye luya kwenzeka xa kukho irekhodi elilodwa kwitafile yokuqala ehambelana nerekhodi enye kwitafile ehambelanayo. Ngokomzekelo, izakhamuzi zase-US zinenombolo yoKhuseleko loLuntu. Kukho inani elilodwa kuphela elinikezelwa ngumntu ngamnye, ngoko ke, umntu akanakunamanani amaninzi.
Nantsi enye umzekelo usebenzisa iileta ezimbini ngezantsi. Itafile zinobudlelwane obulodwa ukuya kwedwa kuba umqolo ngamnye kwitafile yokuqala uhambelana ngqo nomnye umqolo kwitafile yesibili.
| Inombolo yomqeshwa | Igama lokuqala | Ifani |
| 123 | Rick | Rossin |
| 456 | Rob | IHalford |
| 789 | Eddie | Henson |
| 567 | Amy | Bond |
Ngoko inani lemiqolo kumagama omsebenzi wetafile kufuneka lilingane nenani lemiqolo kwiifestile zesebe zabasebenzi.
| Inombolo yomqeshwa | Isikhundla | Ifowuni Ext. |
| 123 | Nxu lumene | 6542 |
| 456 | UMphathi | 3251 |
| 789 | Nxu lumene | 3269 |
| 567 | UMphathi | 9852 |
Olunye uhlobo lohlobo lwe- database lubuhlobo obuninzi ukuya kubaninzi. Ukusebenzisa itafile ephantsi ungabona ukuba uRob Halford, ngumphathi, ngoko ulwalamano lwakhe kwisikhundla sinye ngenxa yokuba kule nkampani umntu unendawo eyodwa kuphela. Kodwa isikhundla sikamagosa siquka abantu ababini, u-Amy Bond noRob Halford, olwalamano olulodwa ukuya kubaninzi. Isikhundla esinye, abantu abaninzi.
Funda kabanzi malunga noLwazi loBudlelwane, iiKhenketho zangaphandle, iiJOINs kunye nee-Diagram .