GRANT, REVOKE kanye neDENY Database Imvume
Ulimi Lokulawulwa Kwedatha (i-DCL) liyisigatshana seLimi Oluhlelekile Lokusebenza (SQL) futhi ivumela abaphathi be-database ukulungisa ukufinyelela kokuphepha kuma-database ehlobene. Iqukethe ulimi lweDatha Definition (DDL), elisetshenziselwa ukwengeza nokususa izinto ezigciniwe, kanye noLwazi lokuPhathwa kwedatha (DML) olusetshenziselwa ukubuyisa, ukufaka, nokuguqula okuqukethwe kwedatha.
I-DCL iyona elula kunazo zonke ze- SQL subsets , njengoba iqukethe imiyalo emithathu kuphela: GRANT, REVOKE, ne-DENY. Okuhlanganisiwe, le miyalo emithathu inikezela abalawuli abanezimo eziguquguqukayo zokusetha nokususa izimvume ezigciniwe kumfashini we-granular ngokweqile.
Ukungeza Izimvume Nge-GRANT Command
Umyalo we-GRANT usetshenziswa ngabalawuli ukwengeza izimvume ezintsha kumsebenzisi wedatha . I-syntax elula, ichazwe kanje:
I-GRANT [ilungelo] ON [into] KUYA [umsebenzisi] [WITH OPANTION]Nansi i-rundown ngayinye yemingcele ongayinika ngalo myalo:
- Ilungelo lingaba yigama elingukhiye BONKE (ukunikeza izimvume ezihlukahlukene) noma imvume ethile yedatha noma isethi semvume. Izibonelo zibandakanya iDATABASE YOKUKHALA, UKUKHETHA, HLELA, HLAWULA, PHALEKA, HLELA futhi YEDA VIEW.
- Into ingaba yinto ethile yedatha. Izinketho ezivumelekile zokukhetha zihluka ngokususelwa kuhlobo lento ye-database oyifaka kulo mshwana. Ngokujwayelekile, into ezoba yinkcazelo, umsebenzi, inqubo egcinwe , ithebula noma umbono.
- Umsebenzisi kungaba yimuphi umsebenzisi wedatha. Ungaphinda ubeke indima kumsebenzisi kulo mshwana uma ufisa ukusebenzisa ukusetshenziswa kokuvikeleka kwedatha.
- Uma ufaka okukhethwa kukho nge- claver OPTION isigatshana ekupheleni komyalo we-GRANT, awugcini nje unikeze umsebenzisi ocacisiwe izimvume ezichazwe esitatimendeni se-SQL kodwa futhi unikeze umsebenzisi amandla okunikeza lawo mvume efanayo kwabanye abasebenzisi be-database. Ngenxa yalesi sizathu, sebenzisa lesi sigatshana ngokunakekelwa.
Isibonelo, cabanga ukuthi ufisa ukunikeza umsebenzisi uJoe ikhono lokuthola ulwazi kusuka kuthebula labasebenzi ku-database ebizwa ngokuthi i-HR. Ungasebenzisa umyalo olandelayo we-SQL:
UKUQALA UKUKHETHA KU-HR.employees KUJoeUJoe manje uzokwazi ukuthola imininingwane etafuleni labasebenzi. Nokho, ngeke akwazi ukunikeza abanye abasebenzisi imvume yokuthola ulwazi oluvela kuleso tafula ngoba awufaki i-clause OPTION isigatshana esitatimendeni se-GRANT.
Ukuphikisa i-Database Access
Umyalo we-REVOKE usetshenziselwa ukususa ukufinyelela kwedatha kusuka kumsebenzisi ngaphambilini owanikezwe ukufinyelela okunjalo. I-syntax yalo myalo ichazwa kanje:
HLAWULA [UKUQALA OKUKHENZISWA] [imvume] ON [into] FROM [umsebenzisi] [CASCADE]Nasi i-rundown kwimingcele yomyalo we-REVOKE:
- Imvume ichaza izimvume ze-database ezizosuswa kumsebenzisi obonisiwe. Umyalo uvuselela kokubili ukuqinisekiswa kwe-GRANT ne-DENY okwenziwe ngaphambili kwemvume ekhonjisiwe.
- Into ingaba yinto ethile yedatha. Izinketho ezivumelekile zokukhetha zihluka ngokususelwa kuhlobo lento ye-database oyifaka kulo mshwana. Ngokujwayelekile, into ezoba yinkcazelo, umsebenzi, inqubo egcinwe, ithebula noma umbono.
- Umsebenzisi kungaba yimuphi umsebenzisi wedatha. Ungaphinda ubeke indima kumsebenzisi kulo mshwana uma ufisa ukusebenzisa ukusetshenziswa kokuvikeleka kwedatha.
- I- GRANT OPTION FOR isigatshana susa ikhono lomsebenzisi ocacisiwe lokunikeza imvume ecacisiwe kwabanye abasebenzisi. Qaphela : Uma ufaka i- GRANT OPTION for isigatshana esitatimendeni se-REVOKE, imvume esemqoka ayikhishwa. Lesi sigaba somthetho sivuselela kuphela ikhono lokunikeza.
- Inketho ye- CASCADE iphinde ivule imvume ecacisiwe kusuka kunoma yimuphi abasebenzisi umsebenzisi ocacisiwe onikeze imvume.
Isibonelo, umyalo olandelayo uvuselela imvume enikwe uJoe kusibonelo sangaphambilini:
HLOLA UKUHLOLA KU-HR.employees KU-JoeUkukhansela ngokucacile Ukufinyeleleka kwedatha
Umyalo we-DENY usetshenziselwa ukuvimbela ngokucacile umsebenzisi ukuthi athole imvume ethile. Lokhu kuyasiza uma umsebenzisi eyilungu leqhaza noma iqembu elinikezwe imvume, futhi ufuna ukuvimbela lo msebenzisi ngamunye ukuba angayifumana ifa lemvume ngokudala okuhlukile. I-syntax yalo myalo ilandelayo:
DENY [imvume] ON [into] KUYA [umsebenzisi] Imingcele yomyalo we-DENY ifana nalabo asetshenziselwa umyalo we-GRANT.
Isibonelo, uma ufisa ukuqinisekisa ukuthi uMathewu akasoze athola ikhono lokususa ulwazi kusuka kuthebula labasebenzi, supha umyalo olandelayo: