NOT NULL- This constraint is responsible for a column to confirm that a
column cannot have a null value.
Example-
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
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