Impela, nansi indlela esingahlela ngayo indatshana oyicelile. Njengoba lokhu kuwumphumela wokucatshangelwa hhayi ikhodi yangempela, qaphela ukuthi noma yiziphi izibonelo zekhodi ezisetshenzisiwe ziyimifanekiso futhi azihloselwe ukuthi zisebenze.
I-Oracle SQL iwulimi olunamandla, olunikeza ikhono lokuphatha kahle, ukukhohlisa nokuhlaziya idatha kusizindalwazi esihlobene. Umsebenzi owodwa ovamile onjiniyela abavame ukuhlangana nawo ukulungisa uhlobo lwedatha lwekholomu. Ku-SQL, umyalo we-ALTER TABLE usetshenziselwa ukwengeza, ukususa/ukwehlisa, noma ukuguqula amakholomu kuthebula elikhona. Umyalo uyasetshenziswa futhi ekuguquleni uhlobo lwedatha lwekholomu.
Inqubo yokushintsha izinhlobo zamakholomu ku-Oracle SQL ibandakanya izinyathelo ezimbalwa: okokuqala sidinga ukuqinisekisa ukuthi ithebula alifinyelelwa ngesikhathi soshintsho, bese kufanele sakhe ikholomu yesikhashana ngohlobo olusha lwedatha, sisuse idatha kusuka kukholomu endala kuya kwentsha, silahle ikholomu endala, futhi siqambe kabusha entsha. ikholomu egameni lokuqala.
ALTER TABLE table_name
ENGEZA_ikholomu_yedatha_uhlobo_olusha;
BUYEKEZA igama_lethebula
SET temp_column = CAST(original_column AS new_data_type);
ALTER TABLE table_name
YENZA COLUMN ikholomu_yoqobo;
ALTER TABLE table_name
RENAME COLUMN temp_column TO original_column;
Ukuqonda i-ALTER TABLE Command
Umyalo we-ALTER TABLE wumyalo we-DDL (Data Definition Language) futhi usetshenziselwa ukwengeza, ukususa/ukwehlisa noma ukuguqula amakholomu kuthebula elikhona. Iphinde isetshenziselwe ukwengeza nokulahla izithiyo kanye nezinkomba kuthebula. I-syntax yomyalo we-ALTER TABLE iqondile. Iqala ngokuthi “ALTER TABLE”, ilandelwe yigama lethebula elizoshintshwa, bese kuba isenzo okumele senziwa.
Inqubo Yokuguqulwa Kwekholomu
Ukuchazwa kabusha kwamakholomu akuyona inqubo yokukhishwa okukodwa, kodwa ukulandelana okuhleliwe kwezinyathelo. Okokuqala, ikholomu yesikhashana iyakhiwa esakhiweni setafula. Le kholomu yesikhashana inikezwe uhlobo olusha lwedatha. Isinyathelo esilandelayo ukuhamba kwedatha. Idatha yekholomu yoqobo iyasuswa noma igcwaliswe kule kholomu yesikhashana esanda kwakhiwa. Kuhle ukuqaphela ukuthi isenzo sokushintsha uhlobo lwedatha yekholomu singase sibe namandla omphumela wokulahlekelwa idatha uma uhlobo olusha lunomthamo omncane kunoludala.
Ukuqonda lezi zinqubo kuhlomisa unjiniyela ngamakhono adingekayo ukuze enze ukukhohlisa kwedatha kumathebula e-Oracle SQL.
Qaphela: Ngenkathi ushintsha uhlobo lwedatha yekholomu, qiniseka ukuthi kunesikhala esanele esitholakalayo esikhaleni setafula ukuze kuhlangatshezwane nenqubo yokuguqulwa kwekholomu. Ukwengeza, ithebula akufanele lifinyelelwe abanye abasebenzisi ngenkathi ulungisa uhlobo lwekholomu.
Imitapo yolwazi ye-Oracle SQL kanye Nemisebenzi Yokukhohlisa Idatha
Kunezinhlobonhlobo zamalabhulali nemisebenzi engasetshenziswa ku-Oracle SQL ukuze kuthuthukiswe inqubo yokukhohlisa idatha. Isibonelo, iphakheji ye-DBMS_REDEFINITION ingasetshenziswa ukwenza ukuchazwa kabusha kwethebula ku-inthanethi, kuyilapho, umsebenzi we-ALTER TABLE…CAST uhlinzeka ngenzuzo yokunika amandla ukuguqulwa kohlobo phakathi kwezinhlobo zedatha ehambisanayo.
Ukuqonda ukusebenza kwala malayibhulali ahlukahlukene kanye nemisebenzi ku-Oracle SQL kuthuthukisa kakhulu ububanzi bokuphatha idatha kanjiniyela. Qiniseka ukuthi uyazijwayeza futhi uzijwayeze le misebenzi ukuze uthole okuningi kuhambo lwakho lwe-Oracle SQL.
Khumbula: I-SQL iyinkambu ebanzi enemisebenzi eminingi. Ungazibekeli emiyalweni eyisisekelo. Hlala uvulekele ukuhlola nokufunda imisebenzi emisha namalabhulali.
