SQL DEFAULT

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

The default value will be added to all new records IF no other value is specified.

Example :

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

The DEFAULT constraint can also be used to insert system values, by using functions like GETDATE():

CREATE TABLE Orders (
    ID int NOT NULL,
    OrderNumber int NOT NULL,
    OrderDate date DEFAULT GETDATE()
);

DROP a DEFAULT Constraint

To drop a DEFAULT constraint, use the following SQL:

ALTER TABLE Persons
ALTER City DROP DEFAULT;

SQL Server / Oracle / MS Access:

ALTER TABLE Persons
ALTER COLUMN City DROP DEFAULT;