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SQL NOT NULL Constraint


this is a table section can hold NULL values.


SQL NOT NULL Constraint

The NOT NULL requirement authorizes a segment to NOT acknowledge NULL values.

The NOT NULL requirement authorizes a field to dependably contain an esteem. We can't embed another record, or refresh a record without increasing the value of this field.

The following SQL authorizes the "User_Id" section and the "FirstName" segment to not acknowledge NULL values:

Example

Make TABLE PersonsNotNull
(
User_Id int NOT NULL,
FirstName varchar(255) NOT NULL,
UserName varchar(255),
Email Address varchar(255),
Secret phrase varchar(255)
)