NOT NULL- This constraint is responsible for a column to confirm that a column cannot have a null value.
Following we create new table PRODUCT and add six columns where ID, SKU, TITLE, PRICE specify not to accept NULLs.
CREATE TABLE PRODUCT
ID INT NOT NULL,
SKU VARCHAR(20) NOT NULL,
TITLE VARCHAR(200) NOT NULL,
PRICE MONEY NOT NULL,
DISCRIPTION VARCHAR(2000) NULL,
DTCREATE DATETIME NULL
If PRODUCT table already created, then to add a NOT NULL constraints to SKU column we use following query.
ALTER TABLE PRODUCT ALTER COLUMN SKU VARCHAR (20) NOT NULL