To answer this question, you need to understand the different types of constraints in Oracle.
Let's go through each option to understand why it is correct or incorrect:
Option A) CASCADE - This option is incorrect because CASCADE is not a valid constraint type in Oracle. It is used in the context of referential integrity to specify that changes made to a primary key value are automatically propagated to the foreign key values.
Option B) UNIQUE - This option is correct. The UNIQUE constraint ensures that all values in a column or a set of columns are unique. It allows for null values but does not allow duplicate values.
Option C) NONUNIQUE - This option is incorrect because NONUNIQUE is not a valid constraint type in Oracle. It is not used to define a constraint.
Option D) CHECK - This option is correct. The CHECK constraint is used to specify a condition that must be true for each row in a table. It allows you to define custom validation rules for the data in a column.
Option E) PRIMARY KEY - This option is correct. The PRIMARY KEY constraint is used to uniquely identify each row in a table. It enforces the uniqueness of values in a column or set of columns and also ensures that the values are not null.
Option F) NOT NULL - This option is correct. The NOT NULL constraint is used to ensure that a column does not contain any null values. It enforces the requirement that the column must have a value for every row.
The correct answer is B, D, E, F. These options are correct because they represent valid constraint types in Oracle.