CONSTRAINT
ADD CONSTRAINT
Yaratish uchun ADD CONSTRAINT buyrug‘idan foydalaniladi
Jadval allaqachon yaratilgandan keyin cheklov.
Quyidagi SQL "PK_Person" nomli cheklovni qo‘shadi, bu bir nechta ustunlar (ID va Familiya) uchun ASOSIY KEY cheklovi hisoblanadi:
Misol
ALTER TABLE Persons
ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);
DROP CONSTRAINT
DROP CONSTRAINT buyrug‘i UNIQUE, PRIMARY KEY, FOREIGN KEY yoki CHECK cheklovini o‘chirish uchun ishlatiladi.
UNIQUE cheklovini o‘chirish (DROP)
UNIQUE cheklovini o‘chirish uchun quyidagi SQL’dan foydalaning:
SQL Server / Oracle / MS Access:
ALTER TABLE Persons
DROP CONSTRAINT UC_Person;MySQL:
ALTER TABLE Persons
DROP INDEX UC_Person;
PRIMARY KEY cheklovini o‘chirish (DROP)
PRIMARY KEY cheklovini o‘chirish uchun quyidagi SQL’dan foydalaning:
SQL Server / Oracle / MS Access:
ALTER TABLE Persons
DROP CONSTRAINT PK_Person;MySQL:
ALTER TABLE Persons
DROP PRIMARY KEY;FOREIGN KEY cheklovini o‘chirish (DROP)
FOREIGN KEY cheklovini o‘chirish uchun quyidagi SQL’dan foydalaning:
SQL Server / Oracle / MS Access:
ALTER TABLE Orders
DROP CONSTRAINT FK_PersonOrder;MySQL:
ALTER TABLE Orders
DROP FOREIGN KEY FK_PersonOrder;CHECK cheklovini o‘chirish (DROP)
CHECK cheklovini o‘chirish uchun quyidagi SQL’dan foydalaning:
SQL Server / Oracle / MS Access:
ALTER TABLE Persons
DROP CONSTRAINT CHK_PersonAge;MySQL:
ALTER TABLE Persons
DROP CHECK CHK_PersonAge;W3Schools Pathfinder
Yutuqlaringizni kuzating – bu bepul!