SQL DEFAULT Constraint

SQL DEFAULT Constraint:

The DEFAULT constraint is used to set a default value for a column.

The default value will be added to all new records, if no other value is specified

SQL DEFAULT on CREATE TABLE:

CREATE TABLE Persons (ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
City varchar(255) DEFAULT 'Sandnes'
);

SQL DEFAULT on ALTER TABLE:

ALTER TABLE Persons ALTER City SET DEFAULT 'Sandnes';

DROP a DEFAULT Constraint:

ALTER TABLE Persons ALTER City DROP DEFAULT;