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NOT NULL Keyword

Not Null

The NOT NULL

constraint enforces a column to not accept NULL values, which means that you cannot insert or update a record without adding a value to this field. The following SQL ensures that the "ID", "LastName", and "FirstName" columns will NOT accept NULL values:

Example

CREATE TABLE Persons ( ID int NOT NULL, LastName varchar(255) NOT NULL,

FirstName varchar(255)

NOT NULL,

Age int

);
The following SQL creates a NOT NULL constraint on the "Age" column when the "Persons" table is already created:

ALTER TABLE Persons

MODIFY Age int NOT NULL;

SQL NOT NULL Keyword

SQL NOT NULL Keyword

NOT NULL Keyword

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Not Null

The NOT NULL

Example

FirstName varchar(255)

Age int

ALTER TABLE Persons

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SQL NOT NULL Keyword

SQL NOT NULL Keyword

NOT NULL Keyword

Previous

Next

Not Null

The NOT NULL

Example

FirstName varchar(255)

Age int

ALTER TABLE Persons

Previous

Next