MySQL

Ukuthola nokuphatha okufakiwe okuyimpinda kusizindalwazi se-MySQL yinkinga evamile abathuthukisi abaningi ababhekana nayo. Akusizi nje kuphela ekugcineni ukufana nobuqotho bedatha, kodwa futhi kuthuthukisa ukusebenza kahle kwedatha yedatha. Kulesi sihloko, sizocubungula indlela, umhlahlandlela wesinyathelo ngesinyathelo, futhi sichaze ukuthi ikhodi ehambisanayo isebenza kanjani.

Lapho usebenzisana nenani elikhulu ledatha kusizindalwazi se-MySQL, okufakiwe okuyimpinda kungavela kaningi. Lezi zimpinda zingadala ukungahambisani nokudideka ngesikhathi sokusebenza kwedatha, ngakho-ke kubalulekile ukuthi sikuthole futhi sikuphathe ngempumelelo. Lo msebenzi ungaba inselele impela, kodwa ngosizo lwemisebenzi ehlukile ye-SQL nemitapo yolwazi, inqubo ingenziwa ibe lula kakhulu.

SELECT column_name, COUNT(*)
FROM table_name
GROUP BY column_name
HAVING COUNT(*) > 1;

Le ngxenye yekhodi iwumbuzo olula we-SQL ongasetshenziswa ukuthola okufakiwe okuyimpinda kunoma iyiphi ikholomu yethebula le-MySQL. I KHETHA isitatimende sisetshenziselwa ukucacisa ikholomu esifuna ukuhlola izimpinda zayo. I I-GROUP BY isigatshana sihlanganisa idatha kukholomu eshiwo kanye ne UKUVULA isigatshana sisetshenziselwa ukuhlunga imiphumela ukubonisa kuphela okufakiwe lapho isibalo singaphezu kokukodwa, okubonisa impinda.

Funda kabanzi

Izingqinamba ezibalulekile zakwamanye amazwe ziyingxenye ebalulekile yokuphatha ubudlelwano kusizindalwazi. Ukungaqondi kahle noma ukuphatha kabi lezi zingqinamba kungaholela kudatha namaphutha anganembile. Ngakho-ke, kubalulekile ukubamba indlela yokuphatha lezi zingqinamba ngempumelelo. Ukusebenzisa amandla e-SQL kungasiza ukwenza lula le nqubo ngokunikeza indlela eqondile yokukhubaza izingqinamba zokhiye bangaphandle uma kudingeka.

Funda kabanzi

Izinqubo ezigciniwe ziyingxenye ebalulekile ye-SQL, ulimi oludumile lokuhlela olusetshenziswa ekulawuleni imininingwane. Inqubo egciniwe ku-SQL ayilutho ngaphandle kweqembu lezitatimende ze-SQL ezakha iyunithi enengqondo futhi zenze umsebenzi othile. Njengamanje, kufanele ube nokuqonda okuyisisekelo kokuthi ziyini Izinqubo Ezigciniwe, nokuthi kungani zibalulekile ezinhlelweni ze-SQL. Kulesi sihloko, sizongena sijule emcabangweni wokuyeka inqubo egciniwe.

Funda kabanzi

Impela, masingene emsebenzini we-SQL 'ALTER TABLE ADD COLUMN' ophathelene nokwengeza amakholomu amasha kuthebula lesizindalwazi esikhona. Lesi sici sibaluleke kakhulu ngoba, ezimweni eziningi, ukwakheka kwethebula lesizindalwazi kungase kudingeke ukuthi kushintshwe ngemva kokudalwa kwalo. Kuhlanganisa ukwengeza ikholomu entsha ukugcina ulwazi olwengeziwe noma ukususa ikholomu uma ingasadingeki. Ngakho-ke, umyalo we-ALTER TABLE uyithuluzi elibalulekile ku-SQL lokuphathwa ngempumelelo kwesizindalwazi.

Funda kabanzi

Impela, nakhu:

Emhlabeni wokuphathwa kwesizindalwazi kanye nokuphatha, igama elilodwa okungenzeka uke wahlangana nalo 'lilungelo elishisayo'. Le nqubo iyingxenye ebalulekile yokuphathwa kwezokuphepha. Inika amandla iseva yedathabheyisi ukuthi ilayishe kabusha amalungelo avela kumatafula esibonelelo kusizindalwazi se-MySQL ngaleyo ndlela iqinisekise ukuthi noma yiziphi izinguquko ezenziwe zisebenza ngokushesha.

Funda kabanzi

In SQL, ulimi olunamandla nolusetshenziswa kabanzi ekulawuleni izizindalwazi ezihlobene, umsebenzi owodwa ovamile ukuguqulwa kokuzenzakalelayo kwamakholomu. Ukushintsha kulo mongo kusho ukushintsha idatha esethiwe ngaphambili noma ezenzakalelayo efakwa kukholomu lapho kungekho datha ethile enikeziwe. Lolu hlobo lokulungiswa kolwazi lwakha ingxenye ebalulekile yokuphatha nokulungisa kahle ukuqoqwa nokucutshungulwa kwedatha, okusiza ukuqinisekisa ukuthi izinhlelo zesizindalwazi ziyasebenza futhi zenziwe kahle.

Funda kabanzi

Ekuphathweni kwesizindalwazi, umsebenzi ojwayelekile ovame ukubhekana nawo onjiniyela ukuthola nokukhomba amathebula athile kusizindalwazi ngamagama abo. Lo msebenzi ubalulekile ezimeni ezinjengokulungisa iphutha, ukuhlanzwa kwedatha, ukwenza ngcono ngisho nasekubhaleni i-schema sedathabhesi. I-SQL, ulimi olujwayelekile lokuphatha nokuphatha imininingwane egciniwe yobudlelwano, inikeza izixazululo zepragmatic kuleyo misebenzi.

Funda kabanzi

Impela, nalu uhlaka lwendatshana kumyalo we-SQL “PROSYS”. Noma qaphela nje ukuthi “PROSYS” akuwona umyalo we-SQL ojwayelekile Nokho, ngizobeka umyalo nenqubo ye-SQL ejwayelekile.

Emhlabeni wesizindalwazi, i-SQL iwulimi oluvelele olusetshenziswa amabhizinisi amaningi nabathuthukisi ukuze basebenzise futhi bahlele idatha. I-SQL, imele Ulimi Lombuzo Ohlelekile, iwulimi oluklanyelwe ukuxhumana nesizindalwazi. Ihlukaniswa njengolimi olujwayelekile lwezinhlelo zokuphathwa kwesizindalwazi esihlobene, njengoba kumenyezelwe yi-ANSI.

Funda kabanzi