Tsayin UNIQUE SQL

Tsayin UNIQUE SQL

UNIQUE kiwon na a kirkira kama da kowacce kowacce a kirkira tabi ko amma kowacce

UNIQUE kiwon da da PRIMARY KEY kiwon na a kirkira kiwon kama da kowacce a kirkira tabi ko amma kowacce

PRIMARY KEY kiwon na a kirkira UNIQUE kiwon

kaidawo, kowacce tabi ko amma kowacce tabi ko amma kowacce PRIMARY KEY kiwon

UNIQUE kiwon a tasiyarin CREATE TABLE

tasiyarin SQL a kan kirkira "Persons" tabi a kirkira UNIQUE kiwon a "Id_P"

MySQL:

CREATE TABLE Persons
(
Id_P int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255),
UNIQUE (Id_P)
)

SQL Server / Oracle / MS Access:

CREATE TABLE Persons
(
Id_P int NOT NULL UNIQUE,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
)

Kamar yadda a baya, don kira UNIQUE kamfani, kuma kira manyan kamfanin UNIQUE, za a yi amfani da kalaman SQL dindindin dindindin:

MySQL / SQL Server / Oracle / MS Access:

CREATE TABLE Persons
(
Id_P int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255),
CONSTRAINT uc_PersonID UNIQUE (Id_P,LastName)
)

Kamfani UNIQUE SQL kan ALTER TABLE

Kamar yadda tabbin da aka kafa, don kawar UNIQUE kamfani a cikin 'Id_P' yanu, za a yi amfani da SQL dindindin dindindin:

MySQL / SQL Server / Oracle / MS Access:

ALTER TABLE Persons
ADD UNIQUE (Id_P)

Don kira UNIQUE kamfani, kuma kira manyan kamfanin UNIQUE, za a yi amfani da kalaman SQL dindindin dindindin:

MySQL / SQL Server / Oracle / MS Access:

ALTER TABLE Persons
ADD CONSTRAINT uc_PersonID UNIQUE (Id_P,LastName)

Kawar UNIQUE kamfani

Don kawar da UNIQUE kamfani, za a yi amfani da SQL dindindin dindindin dindindin:

MySQL:

ALTER TABLE Persons
DROP INDEX uc_PersonID

SQL Server / Oracle / MS Access:

ALTER TABLE Persons
DROP CONSTRAINT uc_PersonID