Examine the following statement that is used to modify the primary key constraint on the SALES table:

Examine the following statement that is used to modify the primary key constraint on the SALES table:
SQL> ALTER TABLE SALES MODIFY CONSTRAINT pk DISABLE VALIDATE; Which three statements are true regarding the above command? (Choose three.)
A. The constraint remains valid.
B. The index on the constraint is dropped.
C. It allows the loading of data into the table using SQL *Loader.
D. New data conforms to the constraint, but existing data is not checked.
E. It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.

Correct Answer: ABC
Explanation/Reference:

Constraint States (continued)
DISABLE NOVALIDATE: New as well as existing data may not conform to the constraint because it is not checked. This is often used when the data is from an already validated source and the table is read-only, so no new data is being entered into the table. NOVALIDATE is used in data warehousing situations where the data has already been cleaned up. No validation is needed, thereby saving time.
DISABLE VALIDATE: If a constraint is in this state, modification of the constrained columns is not allowed because it would be inconsistent to validate the existing data and then allow unchecked data to enter the table. This is often used when existing data must be validated but not modified and when the index is not otherwise needed for performance.
ENABLE NOVALIDATE: New data conforms to the constraint, but existing data is in an unknown state. This is frequently used when it is known that clean and conforming data exists in the table so there is no need for validation. However, new violations are not allowed to enter the system. ENABLE VALIDATE: Both new and existing data conform to the constraint. This is the typical and default state of a constraint.

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