Quick Reference
The ADD keyword is used to add columns or constraints to an existing table.
ADD COLUMN
The following adds the last_name column to the Customers table.
ALTER TABLE Customers
ADD last_name varchar(255);ADD CONSTRAINT
The following adds a constraint named “key_customer” that is a PRIMARY KEY constraint on multiple columns (id and last_name).
ALTER TABLE Customers
ADD CONSTRAINT key_customer PRIMARY KEY (id, last_name);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.