To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) Constraints provide data independence - This option is incorrect because constraints do not provide data independence. Data independence refers to the ability to modify the schema definition without affecting the application programs that use the database. Constraints, on the other hand, are used to enforce rules and maintain data integrity.
Option B) Constraints make complex queries easy - This option is incorrect because constraints do not make complex queries easy. Constraints are used to enforce rules and maintain data integrity, but they do not directly impact the complexity of queries.
Option C) Constraints enforce rules at the view level - This option is correct. Constraints can be defined at the view level to enforce rules on the data displayed by the view. This ensures that only valid data is shown to the users.
Option D) Constraints enforce rules at the table level - This option is correct. Constraints are commonly defined at the table level to enforce rules on the data stored in the table. This ensures that only valid data is stored in the table.
Option E) Constraints prevent the deletion of a table if there are dependencies - This option is correct. Constraints can be used to define dependencies between tables. If there are dependencies, such as foreign key constraints, a table cannot be deleted unless the dependencies are resolved first.
Option F) Constraints prevent the deletion of an index if there are dependencies - This option is incorrect. Constraints do not prevent the deletion of an index. Indexes are used to improve query performance and do not have dependencies like tables.
Therefore, the correct statements about the functions and use of constraints are:
C) Constraints enforce rules at the view level
D) Constraints enforce rules at the table level
E) Constraints prevent the deletion of a table if there are dependencies