Question

If the constraints on the ORDER# and ITEM# columns of the ORDERITEMS table were created as a PRIMARY constraint, and the actual constraint name is not known, which of the following commands can be used to delete the constraint?

A) ALTER TABLE DROP CONSTRAINT
B) DELETE CONSTRAINT
C) DROP CONSTRAINT
D) REMOVE CONSTRAINT

Answer 1

The correct command to delete a PRIMARY key constraint without knowing its name is ALTER TABLE DROP CONSTRAINT, but you need to determine the constraint's name to use this command, which can usually be found in the database's system catalog or information schema.

Step-by-step explanation:

If the constraints on the ORDER# and ITEM# columns of the ORDERITEMS table were created with a PRIMARY key constraint and you don't know the actual name of the constraint, you still have the option to remove it. The correct SQL command from the provided choices would be A) ALTER TABLE DROP CONSTRAINT. However, since you do not know the name of the constraint, the syntax is incomplete. You must know the name of the constraint to drop it using the following syntax:

ALTER TABLE table_name DROP CONSTRAINT constraint_name;

In many database systems, you are able to find the constraint name by querying the database's system catalog or information schema. For instance, in SQL Server, you could use:

SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = 'YourTableName';

Once you have found the constraint name, you can then use the ALTER TABLE command to drop the constraint.