Quick Reference
The DEFAULT keyword provides a default value for a column that will be added to all new records if no other value is specified.
DEFAULT on CREATE TABLE
The following sets a DEFAULT value for the country column when the Customers table is created.
CREATE TABLE Customers (
country varchar(255) DEFAULT 'USA'
);DEFAULT on ALTER TABLE
The following sets a DEFAULT value for the country column when the Customers table already exists.
MySQL:
ALTER TABLE Customers
ALTER country SET DEFAULT 'Canada';SQL Server:
ALTER TABLE Customers
ADD CONSTRAINT df_country
DEFAULT 'Canada' FOR country;DROP a DEFAULT CONSTRAINT
MySQL:
ALTER TABLE Customers
ALTER country DROP DEFAULT;SQL Server:
ALTER TABLE Customers
ALTER COLUMN country DROP DEFAULT;SQL Notes:
- Any work being done to modify the structure of a database or delete tables or the the database itself should only be done after making a recent backup
We’d like to acknowledge that we learned a great deal of our coding from W3Schools and TutorialsPoint, borrowing heavily from their teaching process and excellent code examples. We highly recommend both sites to deepen your experience, and further your coding journey. We’re just hitting the basics here at 1SMARTchicken.