Which of the following can be managed with ALTER TABLE according to the described capabilities?

Which of the following can be managed with ALTER TABLE according to the described capabilities?

• A. Primary key constraint
• B. Creating a view
• C. Dropping a trigger
• D. Creating a database

Answer: (A)

ALTER TABLE is used to change the structure and constraints of an existing table, so it can manage a primary key constraint by adding or altering that constraint on the table. This is how you enforce uniqueness and identify each row after the table already exists; for example, you can define a primary key on one or more columns with a statement like ALTER TABLE employees ADD CONSTRAINT pk_employees PRIMARY KEY (employee_id). The other actions aren’t done with ALTER TABLE: creating a view, dropping a trigger, or creating a database require separate statements (CREATE VIEW, DROP TRIGGER, CREATE DATABASE), not altering the table itself.

ALTER TABLE is used to change the structure and constraints of an existing table, so it can manage a primary key constraint by adding or altering that constraint on the table. This is how you enforce uniqueness and identify each row after the table already exists; for example, you can define a primary key on one or more columns with a statement like ALTER TABLE employees ADD CONSTRAINT pk_employees PRIMARY KEY (employee_id).

The other actions aren’t done with ALTER TABLE: creating a view, dropping a trigger, or creating a database require separate statements (CREATE VIEW, DROP TRIGGER, CREATE DATABASE), not altering the table itself.