ALTER TABLE Sale
ADD CONSTRAINT ValidDiscount
CHECK(discount <= unit_price *0.2);
This is ANSI 92, but IIRC not all RDBMS support it... MySQL doesn't.
Frage
My table structure is as follows:
create table Sale(
id int primary key,
product_ID int foreign key references ItemCategory.Item_Details(item_id),
product_name varchar(10),
unit_price int,
quantity int,
discount int,
total_price int,
profit int
)
Now I have to implement the following constraints in the sale table: The discount offered on a product should not be greater than 20% of the unit price of the product.
Lösung
ALTER TABLE Sale
ADD CONSTRAINT ValidDiscount
CHECK(discount <= unit_price *0.2);
This is ANSI 92, but IIRC not all RDBMS support it... MySQL doesn't.