Ukusebenzisa i-Wildcards ngokungafanisani
Ukufaniswa kwefayile ye-SQL kukuvumela ukukhangela iipatheni kwidatha, ukuba awukwazi igama elichanekileyo okanye ibinzana olifunayo. Olu hlobo lwemibuzo ye-SQL isebenzisa izinhlamvu ze-wildcard ukuze zifanise iphethini, kunokuba zicacise ngokuchanekileyo. Ngokomzekelo, ungasebenzisa i-wildcard "C%" ukufanisa nayiphi na intambo eqala ngeC capital.
Ukusebenzisa i-LIKE Operator
Ukusebenzisa ibinzana le-wildcard kwisicelo se-SQL, sebenzisa umsebenzisi we-LIKE kwisiqendu se-WHERE, uze ufakele iphethini kumanqaku athile okucaphuna.
Ukusebenzisa i-% Wildcard Ukwenza Usesho olulula
Ukukhangela nawuphi na umsebenzi kwisiseko sakho segama kunye negama lokugqibela eqala ngeleta C, sebenzisa le nkcazo elandelayo yeTransact-SQL:
UKUKHETHA * KWABAFUNDI ABAKHO apho igama_kugqibela igama elithi 'C%'Ukufakela iipatheni ngokusebenzisa igama elingundoqo
Sebenzisa igama elingundoqo ukuba ukhethe iirekhodi ezingafani nomzekelo. Umzekelo, lo mbuzo ubuyisela zonke iirekhodi ogama lakhe lokugqibela aliqalanga ngeC:
UKUKHETHA * KWABASEBENZI ABAKHO igama lokugqibela_FUNA 'IK%%'Ukufanisana nePatheni Naphi na usebenzisa i-Wildcard kabini
Sebenzisa iziganeko ezimbini ze-wildcard ukuze ufanise iphethini ethile. Lo mzekelo ubuyisela zonke iirekhodi eziqulethwe yiC apho naphina egameni lokugqibela:
UKUKHETHA * KWABASEBENZI ABAPHAKATHI apho igama_kuthi igama elithi '% C%'Ukufumana umxube wePateni kwindawo ethile
Sebenzisa i-wildcard ukubuyisela idatha kwindawo ethile. Lo mzekelo uhambelana kuphela xa iC ivela kwindawo yesithathu yekholomu yegama lokugqibela:
UKUKHETHA * KWABAFUNDI ABAPHAKATHI apho igama_kuthi igama '_ _C%'Imifanekiso ye-Wildcard exhaswayo kwi-Transact SQL
Kukho iintlobo zee-wildcard ezixhaswa yi-Transact SQL:
- I- % yendawo ye-wildcard idibanisa i-zero okanye iindidi ezingaphezulu kwanoma yiluphi uhlobo, kwaye ingasetyenziselwa ukuchaza i-wildcards zombini ngaphambi nangemva kwephethini. Ukuba uqhelanise ne-DOS yokufanisa iphethini, lilingana ne-wildcard kule syntax.
- I-wildcard idibanisa ngokufanayo uhlobo olulodwa lwaluphi uhlobo. Ingalingani na ? i-wildcard kwi-DOS yokufanisa iphethini.
- Cacisa uluhlu lwabalinganiswa ngokuzifakela kwiibakaki zesikwele. Ngokomzekelo, i-wildcard [aeiou] ihambelana naluphi na isibonakaliso.
- Cacisa uluhlu lwabalinganiswa ngokufaka uluhlu kwiibakaki zesikwere. Umzekelo, i-wildcard [idibana] nayiphi na ileta kwisiqingatha sokuqala se-alfabhethi.
- Nciphisa uluhlu lwabalinganiswa ngokubandakanya umlinganisi we-carat ngokukhawuleza ngaphakathi kwesikhonkwane sokuvula. Ngokomzekelo, [^ aeiou] ufanisana naluphi na umgca ongekho umlindo ngelixa [^ u] uhambelana naluphi na uhlobo olungenalo kwisiqingatha sokuqala sealfabhethi.
Ukudibanisa i-Wildcards kwiimodeli ezidibeneyo
Hlanganisa la ma-wildcards kwiipatheni ezinzima ukwenza imibuzo ephakamileyo. Ngokomzekelo, cinga ukuba ufuna ukwakha uluhlu lwabasebenzi bakho abanamagama aqala ngeleta ukusuka kwisiqingatha sokuqala sealfabhethi kodwa abapheli ngevowuni. Ungayisebenzisa le mibuzo:
UKUKHETHA * KWABASEBENZI ABAKHO igama lokugqibela LIKE '[i]% [^ aeiou]'Ngokufanayo, unokwakha uluhlu lwabaqeshwa bonke abanegama lokugqibela elinamaqela amane ngokusebenzisa iziganeko ezine ze-pattern:
UKUKHETHA * KWABASEBENZI ABAPHAKATHI I-last_name LIKE '____'Njengoko unokukuxelela, ukusetyenziswa kwe-SQL yokufanisa iphethini yokubonelela kubonelela ngabasebenzisi beenkcukacha ze-database ukuba bakwazi ukuhamba ngaphaya kwemibuzo ebhaliweyo yombhalo kwaye benze imisebenzi yokuphenya ephambili.