Isingeniso kuLwazi loLwazi

Igama leenkcukacha "ubudlelwane" okanye "ubudlelwane" luchaza indlela idatha etafileni edibene ngayo.

Abantu abasandul 'ukuza kwihlabathi yolwazi badla ngokukhawuleza babone umahluko phakathi kwedatha kunye nespredishithi. Babona iitafile zedata kwaye baqonda ukuba iinkcukacha zolwazi ziyakuvumela ukuba uququzelele kwaye uphendule idatha ngeendlela ezintsha, kodwa uhluleke ukuqonda ukubaluleka kobudlelwane phakathi kwedatha enikezela iteknoloji yezobuchwepheshe.

Ubudlelwane buyakuvumela ukuba uchaze ukudibanisa phakathi kwetafile zeenkcukacha ezahlukeneyo ngeendlela ezinamandla. Olu lwalamano lunokuthi lube lusetyenziswe ukwenza imibuzo enamandla yeetable-table, eyaziwa ngokujoyina.

Iintlobo zoLwazi loLwazi

Kukho iintlobo ezintathu ezahlukeneyo zobudlelwane beenkcukacha, ngamnye ubizwa ngokubhekiselele kwinani lamatafula etafile angabandakanyeka kulwalamano. Ngolunye lwezi ntlobo zobudlelwane ezintathu zikhoyo phakathi kweetrafile ezimbini.

• Ulwalamano olulodwa ukuya kolunye lwenzeka xa ngamnye ukungena etafileni yokuqala kunomnye, kwaye omnye kuphela, umlingani kwitheyibhile yesibini. Ulwalamano olulodwa kunye nolunye lunqabile lisetyenziswe kuba luhlala lusebenza ngokugqithiseleyo ukubeka yonke inkcazelo kwitafile enye. Abanye abenzi beenkcukacha zedatha bawasebenzisa ngokunxulumene lobu budlelwane ngokudala iitafile eziqulethe i-subset yedatha evela kwelinye itafile.
• Ulwalamano olulodwa ukuya kubaninzi luhlobo oluqhelekileyo lwentsapho yolwazi. Zenzeka xa irekhodi ngalinye kwiThebhile A lihambelana neerekhodi enye okanye ngaphezulu kwiTheyibhile B, kodwa irekhodi ngalinye kwiTable B lihambelana nerekodi enye kwiTable A. Ngokomzekelo, ubudlelwane phakathi kwetafula zetitshala kunye nabafundi batyelela kwisikolo saseprayimari Isiseko semfundo singaba sisisombululo esisodwa, kuba ngamnye umfundi unomfundisi omnye kuphela, kodwa ngamnye utitshala unabafundi abaninzi. Ukuqulunqwa komntu omnye kuya kunceda ukuqeda idatha ephindiweyo.

• Ulwalamano oluninzi kuninzi luba khona xa irekhodi ngalinye kwiTable A lihambelana neerekhodi enye okanye ngaphezulu kwiTheyibhile B, kwaye irekhodi ngalinye kwiTable B lihambelana neerekhodi enye okanye ngaphezulu kwiTheyibhile A. Ngokomzekelo, ubudlelwane phakathi kootitshala kunye neekhosi Itheyibhile iya kuba yinkoliso yamaninzi ngenxa yokuba utitshala ngamnye unokuyalela iikhosi ezingaphezu kweyodwa, kwaye ikhosi nganye inokuba nomfundisi omnye.

Ulwalamano lokuzimela ngokuzimela: Kwimeko ekhethekileyo

Ulwalamano oluzimelayo lwenzeka xa kukho itafile enye echaphazelekayo. Omnye umzekelo oqhelekileyo uluhlu lwebasebenzi oluqulethe ulwazi malunga nomphathi wesebenzi ngamnye. Umphathi ngamnye umqeshwa kwaye unomphathi wakhe. Kule meko, kukho ulwalamano oluzimeleyo ukuya kubaninzi, njengoko umqeshwa ngamnye unomphathi wesinye, kodwa umphathi ngamnye unokuba nomqeshwa omnye.

Ukudala ubudlelwane kunye neeKhenketho zangaphandle

Udala ubudlelwane phakathi kweetyuli ngokucacisa ukhiye wangaphandle. Olu litshixo luxelela i-database yolwazi ukuba iileta zihambelana njani. Kwiimeko ezininzi, ikholomu kwiThebhile A iqukethe izitshixo eziphambili ezibhekiselelwe kwiTable B.

Khawucinge kwakhona ngomzekelo wabaTitshala kunye nabafundi betafile. Itafile zeTitshala ziqulethe i-ID kuphela, igama, kunye nekholamu yekhosi:

Abafundi betafile baquka i-ID, igama, kunye nekholamu yangaphandle yesiqalo:

Ikholamu Teacher_FK kwietafile zabafundi ibonakalisa ixabiso eliphambili le-key of the instructor kwitheyibhile yootitshala.

Ngokuqhelekileyo, abayili beenkcukacha basebenzisa i-"PK" okanye "FK" kwigama lekholomu ukuchonga ngokulula ukhiye oyintloko okanye ikholomu yangaphandle.

Qaphela ukuba ezi zibhebhile ezimbini zibonisa ubuhlobo obuninzi ukuya kubaninzi phakathi kootitshala nabafundi.

Ubudlelwane kunye noBungqina bokuBambisana

Emva kokuba ungeze ukhiye wangaphandle kwitafile, ungayenza i-contrainteti ye-database eqinisekisa ukuthembeka kwentembeko phakathi kweetafile ezimbini. Oku kuqinisekisa ukuba ubudlelwane phakathi kwetafile buhlala buvumelana. Xa itheyibhile enye inekona yangaphandle kwelinye itafile, umgaqo wokuthembeka uthetha ukuba nayiphi na ixabiso elingundoqo langaphandle kwiThebhile B kufuneka libhekise kwiirekhodi ekhoyo kwiTable A.

Ukuzalisa ubudlelwane

Ngokuxhomekeke kwisiseko sakho, uzalisekisa ubudlelwane phakathi kwetafile ngeendlela ezahlukeneyo. I-Microsoft Access inikezela idijithi evumela ukuba udibanise iitheyibhile kunye nokunyanzelisa ukuthembeka.

Ukuba ubhala i-SQL ngokuthe ngqo, uza kuqala udala iitheyibhile ootitshala, uvakalise ikholamu ye-ID ukuba yintloko ephambili:

YADALA ABAKHULU OLAWULO (

I-InstructorID INT AUTO_INCREMENT IPRAYIMARI EYIKHULU,
Teacher_Name VARCHAR (100),
I-Course VARCHAR (100)
);

Xa udala abafundi betafile, uvakalisa ikholomu ye-Teacher_FK ukuba yikhiye yangaphandle ekhankanya ikholomu ye-InstructorID kwitafile yaTitshala:

YADALA ABAFUNDI ABAKHULU (
I-StudentID INT AUTO_INCREMENT IPRAYIMARI EYIKHULU,
Umfundi_Name VARCHAR (100), Teacher_FK INT,
ISIHLOKO ESIKHULUMENTE (Teacher_FK) UKUFUNA KWABAFUNDI (Ootitshala) (I-InstructorID))
);

Ukusebenzisa ubudlelwane ukujoyina iiTables

Emva kokuba udale ubudlelwane obunye okanye obuninzi kwi-database yakho, unokusebenzisa amandla abo ngokusebenzisa imibuzo ye-SQL JOIN ukudibanisa ulwazi oluvela kumatafula amaninzi. Uhlobo oluqhelekileyo lokujoyina luyi-SQL INNER JOIN, okanye ukujoyina okulula. Olu hlobo lokujoyina lubuyisela zonke iirekhodi ezidibanisa imeko yokujoyina kwiitheyibhile ezininzi. Ngokomzekelo, lo MSEBENZI uya kubuya umfundi we-Student_Name, Teacher_Name, kunye neKhosi apho ikhefu langaphandle kwitafile zabafundi lifana neyona nto ephambili kwitafile zootitshala:

UKUHLOLA Abafundi.Student_Name, Ootitshala.Teacher_Name, TeachersCourse
KWABAFUNDI
INNER JOIN Ootitshala
KWABAFUNDI.Teacher_FK = Ootitshala.IsiXhobo;

Le ntetho ivelisa itafile into enje:

Ithebula elibuyiselwe kwiSQL Joyina Statement

Student_NameTeacher_NameCourseLowell SmithJohn DoeEnglishBrian ShortJohn DoeEnglishCorky MendezJane SchmoeMathMonica JonesJohn DoeEnglish