SQL NOT NULL Keyword
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SQL NOT NULL Keyword
❮ SQL Keywords Reference
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
); Try it Yourself »
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 Keywords Reference
