Ukusebenzisa i-Wildcards yokungalingani okungalungile
Ukufaniswa kwephethini ye-SQL kukuvumela ukuthi useshe amaphethini kudatha, uma ungazi igama eliqondile noma inkulumo oyifunayo. Lolu hlobo lombuzo we-SQL lusebenzisa izinhlamvu ze-wildcard ukufanisa iphethini, kunokuba zicacise kahle. Isibonelo, ungasebenzisa i-wildcard "C%" ukufanisa noma yikuphi uhlamvu oluqala nge-capital C.
Ukusebenzisa i-LIKE Operator
Ukuze usebenzise inkulumo ye-wildcard kumbuzo we-SQL, sebenzisa opharetha we-LIKE ku-WHERE clause, bese ufaka iphethini ngaphakathi kwamamaki okucaphuna owodwa.
Ukusebenzisa i-% Wildcard Ukwenza Usesho Olulula
Ukucinga noma yisiphi isisebenzi ku-database yakho enegama lokugcina eqala ngencwadi C, sebenzisa isitatimende esilandelayo se-Transact-SQL:
HLOLA * KUSUKA kwabasebenzi LAPHO last_name LIKE 'C%'Ukufakela Amaphethini Ukusebenzisa ASIgama elingukhiye
Sebenzisa i-KE elingukhiye ukuze ukhethe amarekhodi angafani nephethini. Isibonelo, lo mbuzo ubuyisela wonke amarekhodi ogama lakhe lokugcina aliqali nge C:
HLOLA * KUSUKA kwabasebenzi LAPHO igama_i-NAME_lingafani 'noC%'Ukufanisa i-Pattern Anywhere Ukusebenzisa i-% Wildcard kabili
Sebenzisa izimo ezimbili ze-wildcard % ukufanisa iphethini ethile kuphi. Lesi sibonelo sibuyisela wonke amarekhodi aqukethe iC noma ngabe kuphi egameni lokugcina:
HLOLA * KUSUKA kwabasebenzi LAPHO last_name LIKE '% C%'Ukuthola Ukufaniswa Kwesibonelo Esikhundleni Esiqondile
Sebenzisa i _ wildcard ukuze ubuyele idatha endaweni ethize. Lesi sibonelo sifana kuphela uma i-C ibonakala endaweni yesithathu yekholomu yegama lokugcina:
HLOLA * KUSUKA kwabasebenzi LAPHO last_name LIKE '_ _C%'Amazwi we-Wildcard asekelwe ku-Transact SQL
Kunezinkulumo eziningana ze-wildcard ezisekelwe yi-Transact SQL:
- I-wildcard % ihambisana ne-zero noma izinhlamvu eziningi zanoma yiluphi uhlobo, futhi ingasetshenziselwa ukuchaza amaskredari kokubili ngaphambi nangemva kwephethini. Uma ujwayele ukufaniswa kwephethini ye-DOS, kungalingana ne * wildcard kulelo syntax.
- I _ i- wildcard ihambisana ncamashi nomlingiswa owodwa waluphi uhlobo. Kungalingana ne- ? i-wildcard ekufanisweni kwephethini ye-DOS.
- Cacisa uhlu lwabalingiswa ngokuwafaka kubakaki abesikwele. Isibonelo, i-wildcard [aeiou] ifanelana nanoma iyiphi i-vowel.
- Cacisa ububanzi bezinhlamvu ngokufaka ibanga kubakaki abesikwele. Isibonelo, i-wildcard [ ihambisana ] nanoma iyiphi incwadi engxenyeni yokuqala yezinhlamvu.
- Nciphisa ububanzi bezinhlamvu ngokufaka uhlamvu lwe-carat ngokushesha ngaphakathi kwesibhakela lesikwele. Isibonelo, i- [^ aeiou] ifanelana nanoma yisiphi isilondolozi esingenayo isilawuli ngenkathi i- [^ i] ihambelana nanoma yisiphi isici esingengxenye yokuqala yezinhlamvu.
Ukuhlanganisa ama-Wildcards for Patterns Complex
Hlanganisa lezi zindawo zasendle ezinamaphethini eziyinkimbinkimbi ukwenza imibuzo ephakeme kakhulu. Isibonelo, ake sithi udinga ukwakha uhlu lwabasebenzi bakho bonke abanamagama aqala ngencwadi evela engxenyeni yokuqala yezinhlamvu kodwa angapheli nge-vowel. Ungasebenzisa le mibuzo elandelayo:
HLOLA * KUSUKA kwabasebenzi lapho i-last_name LIKE '[am]% [^ aeiou]'Ngokufanayo, ungakha uhlu lwabaqeshwa abanegama lokugcina eliqukethe izinhlamvu ezine ngokusebenzisa izimo ezine ze-pattern:
HLOLA * KUSUKA kwabasebenzi LAPHO last_name LIKE '____'Njengoba ungatshela, ukusetshenziswa kwe-SQL yokufanisa iphethini kwamakhono kunikezwa abasebenzisi be-database bakwazi ukuhamba ngaphandle kwemibuzo elula yombhalo futhi benze imisebenzi yokuphenya okuphambili.