Oracle Alter Table

The Oracle Alter Table – allow you to add new columns, modify and drop columns, rename table, add constraints.

Oracle Alter Table

Alter Table contracts 
Add approve varchar2(3);
       
Alter Table contracts
Drop column approve;

Alter Table customers 
Set unused (first_name, last_name);

Alter Table customers
add CONSTRAINT fk_user 
FOREIGN KEY (user_id, user_name)
REFERENCES user(user_id, user_name)
ON DELETE CASCADE;