ULwimi loLawulo lweDatha (DCL)

UKUHLAWULWA, UKUVIKELA, kunye neDENY Database Database

ULwimi loLawulo lweDatha (i-DCL) li-subset yoLwimi oluCwangcisiweyo lweeNgxelo (SQL) kwaye luvumela abaphathi beenkcukacha ukuba baqwalasele ukufikelela kokuphepha kwiinkcukacha zolwazi. Izalisekisa uLwimi lweNkcazo yoLwazi (iDDL), elisetyenziselwa ukongeza nokucima izinto zeenkcukacha, kunye neLwimi yokuLawulwa kweData (iDML) esetyenziselwa ukubuyisa, kufaka, nokuguqula okukuko kwedatha.

I-DCL yindlela elula kunazo zonke ze- SQL , njengoko iqukethe imiyalelo emithathu kuphela: I-GRANT, REVOKE, ne-DENY. Ukudibanisa, le miyalelo emithathu inikezela abalawuli nge-flexibility ukusetha nokususa iimvume zedatha kwifashoni ekhulu kakhulu.

Ukongeza iimvume kunye ne-GRANT Command

Umyalelo we-GRANT usetyenziswa ngabalawuli ukufaka iimvume ezintsha kumsebenzisi wolwazi . It has syntax elula, ichazwe ngale ndlela:

UKUFUNA [ilungelo] KUYO [into] KUYA [umsebenzisi] [NGOKUKHENZISWA KWE-GRANT OPTION]

Nantsi ingqungquthela kwiiparitha nganye ongayihambisa ngalo myalelo:

• Ilungelo lingaba ligama elingundoqo (ALL granting various types of permissions) okanye imvume ethile yedatha okanye isethi semvume. Iimzekelo ziquka ukudala iDATABASE, UKUKHETHA, UKUBHALA, UKUPHATHA, UKUCACISA, UKUQALA, UKUKHONA.
• Into ingaba nayiphi na into egciniweyo. Izinketho ezikhethiweyo ezikhethiweyo ziyahlukahluka ngokubhekiselele kumhlobo wolwazi lwezinto ezifakwe kulo mhlathi. Ngokuqhelekileyo, into iya kuba yinkcukacha, umsebenzi, inkqubo egcinwe , itafile okanye umbono.
• Umsebenzisi unakho nawuphi na umsebenzisi wolwazi. Ungatshintsha indima kumsebenzisi kulo mhlathi xa unqwenela ukusebenzisa i-database-based based security.
• Ukuba uquka okukhethiweyo NOMGAQO WENKQUBO YOKUQALA ekupheleni komyalelo we-GRANT, awunikezeli kuphela umsebenzisi ochaziweyo iimvume ezichazwe kwisitatimende se-SQL kodwa kwakhona unike umsebenzisi amandla okunika ezo mvume ezifanayo kwabanye abasebenzisi beenkcukacha. Ngenxa yesi sizathu, se benzisa le gatya ngokunyamekela.

Ngokomzekelo, cinga ukuba unqwenela ukunika umsebenzisi uJoe ithuba lokufumana ulwazi oluvela kubathengi basebenzi kwiziko elibizwa ngokuba yi-HR. Ungasebenzisa umyalelo we SQL olandelayo:

UKUHLOLA UKUHLOLA KU-HR.employees KUJoe

UJoe uya kuba nekhono lokufumana ulwazi oluvela kubathengi basebenzi. Kodwa ke akanako ukunika abanye abasebenzisi imvume yokufumana ulwazi oluvela kule tafile ngoba awuzange ufake i-CLANT OPTION isigatshana kwi-GRANT statement.

UkuPhakamisa i-Database Access

Umyalelo we-REVOKE usetshenziselwa ukususa ukufikelela kwi-database ukusuka kumsebenzisi wangaphambili owanikezelo olunjalo. I-syntax yalo myalelo ichazwa ngale ndlela ilandelayo:

HLAWULA [UKUFUNA UKUVELA] [imvume] [into] FROM [user] [CASCADE]

Nantsi ingqungquthela kwimimiselo ye-REVOKE umyalelo:

• Imvume ichaza imvume yemvume yokususa kumsebenzisi ochongiweyo. Umyalelo uphazamisa zombini iziqinisekiso ze-GRANT kunye ne-DENY ezenziwe ngaphambili kwimvume echongiweyo.
• Into ingaba nayiphi na into egciniweyo. Izinketho ezikhethiweyo ezikhethiweyo ziyahlukahluka ngokubhekiselele kumhlobo wolwazi lwezinto ezifakwe kulo mhlathi. Ngokuqhelekileyo, into iya kuba yinkcukacha, umsebenzi, inkqubo egcinwe, itafile okanye umbono.
• Umsebenzisi unakho nawuphi na umsebenzisi wolwazi. Ungatshintsha indima kumsebenzisi kulo mhlathi xa unqwenela ukusebenzisa i-database-based based security.
• UKUHLOLA OKUQHELEKILEYO Umhlathi uwasusa amandla omsebenzisi ochaziweyo ukuba anike imvume ebhaliweyo kwabanye abasebenzisi. Qaphela : Ukuba uquka INKQUBO YOKWENZA ISIGABA kwisitatimende se-REVOKE, imvume engundoqo ayigxothwanga. Eli gatya livusa kuphela amandla okunika inkxaso.
• Inketho yeCASCADE iphinda ihlaziye imvume echaziweyo kunoma yimuphi umsebenzisi umsebenzisi ochaziweyo unike imvume.

Ngokomzekelo, umyalelo olandelayo uphinda uvule imvume ehanjiswe kuJoe kumzekelo wangaphambili:

HLAWULA UKUHLOLA KU-HR.employees FROM Joe

Ukukhanyela ngokucacileyo ukufikelela kwiDatabase

Umyalelo we-DENY usetyenziswa ukukhusela ngokucacileyo umsebenzisi ekufumaneni imvume ethile. Oku kunceda xa umsebenzisi elungu lendima okanye iqela elinikwe imvume, kwaye ufuna ukukhusela loo mntu ngamnye ukuba angayifumana ifa lemvume ngokudala i-exception. I-syntax yalo myalelo ilandelayo:

DENY [imvume] KUYO [into] KUYA [umsebenzisi]

Iiparameters zomyalelo we-DENY zifana nalawo asetshenziselwa umyalelo we-GRANT.

Umzekelo, ukuba unqwenela ukuqinisekisa ukuba uMateyu akaze athole ukukwazi ukususa ulwazi kwitafile zabasebenzi, supha umyalelo olandelayo:

KUKHULULEKA KWI-HR.employees KuMateyu