Uyisebenzisa kanjani i-SQL Drop, iTruncate kunye nokucima iiNgxelo

I-SQL DELETE ingxelo isetyenziselwa ukucima iirekhodi kwitafile ngelixa DROP Isiteyitimenti sisetyenziselwa ukucima itafile okanye isiseko sedatha.

I TRUNCATE TABLE Isiteyitimenti sinokusetyenziselwa ukucima iirekhodi kwitafile.

Ukucima iirekhodi kwitafile

I DELETE Isiteyitimenti kwi-SQL sisetyenziselwa ukucima iirekhodi ezivela kwitafile yedatha. Singasusa zonke iirekhodi kwitafile okanye sicime iirekhodi ezithile sisebenzisa igatya APHO.

DELETE FROM table_name WHERE condition;

SQL SUSA IMizekelo yeNgxelo

Masicinge ukuba sinetafile ebizwa ngokuba 'ngabasebenzi' ngezi rekhodi zilandelayo:

+------------+-----------+----------+------------+ | EmployeeID | FirstName | LastName | Department | +------------+-----------+----------+------------+ | 1

| Mark
| Otto
| Finance | | 2

| Jacob
| Thornton | IT
| | 3

| Su
| Bird
| Marketing | | 4

| Sam
| Burger | IT
| +------------+-----------+----------+------------+

Cima irekhodi elinye

Le khowudi ilandelayo isusa 'uJacob Thornton' kwitafile 'yabasebenzi':

DELETE FROM Employees WHERE FirstName = 'Jacob' AND LastName = 'Thornton'; Phawula:Kumzekelo ongentla, sisebenzisa iimeko ezimbini, KUPHI kwaye KUNYE Oko kukuthi ngegama lokuqala kwaye Ifani. Oku kukuqinisekisa ukuba siyasusa irekhodi elichanekileyo, ukuba kukho omnye umsebenzi onegama elifanayo.

Cima Zonke iirekhodi kwitafile

Le khowudi ilandelayo icima zonke iirekhodi kwitafile 'Abasebenzi':

DELETE * FROM Employees; Phawula:Inkqubo ye- SUSA ingxelo isusa iirekhodi kwitafile, kodwa ayicimi itafile uqobo.

Ingxelo ye-SQL YOKUQEQESHA I-SQL

I TRUNCATE TABLE Isiteyitimenti sinokusetyenziselwa ukucima iitafile, kodwa hayi itafile endaweni yoko.

Umzekelo:

TRUNCATE TABLE table_name;

Ingxelo yokulahla kwe-SQL

I DROP Ingxelo kwi-SQL isetyenziselwa ukucima itafile okanye isiseko sedatha.

Ulahla njani iTafile kwi-SQL

Le khowudi ilandelayo ilahla itafile ebizwa ngokuba 'ngabasebenzi':

DROP TABLE 'Employees'; Phawula:Thatha inkathalo engaphezulu xa usebenzisa i I-DROP ingxelo. Xa ulahla itafile, iya kucima zonke iirekhodi ngaphakathi kwetafile.

Ulahla njani indawo yogcino lwedatha kwi-SQL

Le khowudi ilandelayo ilahla indawo yedatha ebizwa ngokuba yi 'EmployeesDB':

DROP DATABASE 'EmployeesDB'; Phawula:Thatha inkathalo engaphezulu xa usebenzisa i I-DROP ingxelo. Xa ushiya indawo yogcino lwedatha, iya kucima zonke iitafile ngaphakathi kwiziko ledatha.