To answer this question, you need to understand the concept of Oracle constraints. Oracle provides various types of constraints to enforce rules on the data stored in a table.
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 Oracle constraint type. CASCADE is used with foreign key constraints to define the action to be taken when a referenced row is deleted or updated.
Option B) UNIQUE - This option is correct. UNIQUE is a valid Oracle constraint type that ensures that all values in a column or set of columns are unique.
Option C) NONUNIQUE - This option is incorrect because NONUNIQUE is not a valid Oracle constraint type. The opposite of UNIQUE constraint is actually the default behavior, where duplicate values are allowed.
Option D) CHECK - This option is correct. CHECK is a valid Oracle constraint type that allows you to specify a condition that must be satisfied for the data in a column.
Option E) PRIMARY KEY - This option is correct. PRIMARY KEY is a valid Oracle constraint type that uniquely identifies each row in a table.
Option F) NOT NULL - This option is correct. NOT NULL is a valid Oracle constraint type that ensures that a column cannot contain any NULL values.
The correct answer is B, D, E, F. These options are correct because they represent valid Oracle constraint types.