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Answer the following questions:
                 1.  Can a table have two identical tuples?
                 2.  Consider the table MOVIE given below:
                    +---------+------------------------------+----------+--------+--------------------+
                    | MOVIEID | TITLE                        | LANGUAGE | RATING | PLATFORM           |
                    +---------+------------------------------+----------+--------+--------------------+
                    | M001    | Pushpa: The Rise             | Telugu   |    7.9 | Amazon Prime Video |
                    | M004    | The Mauritanian              | Spanish  |    7.5 | Showtime           |
                    | M010    | Jai Bheem                    | Tamil    |    9.1 | Disney+Hotstar     |
                    | M011    | Spider-Man: No Way Home      | Hindi    |    8.8 | NA                 |
                    | M015    | Thalaivi                     | French   |    6.1 | Netflix             |
                    | M018    | Zack Snyder's Justice League | English  |    8.1 | HBO Max            |
                    +---------+------------------------------+----------+--------+--------------------+
                    What is the degree of the table MOVIE? What is the cardinality of the table MOVIE?



        NULL Value

        If the value for an attribute is unknown for a tuple, DBMS uses the NULL value. An attribute value may be NULL in the
        following situations:
        • The value exists but is currently unknown (for example, DOB).

        • We do not know whether the value exists (for example, landline number).
        • No value is applicable (for example, spouse name for an unmarried employee).
        Note that in DEPARTMENT relation, Mgr_Id corresponding  to the department having Dept_No 3 is NULL as a
        manager has not been assigned to the department having Dept_No 3.
        As mentioned above, a key identifies a tuple in a table uniquely. Attributes that are part of the key are known as key

        attributes. When a key has more than one attribute, it is called a composite key. For example, in the relation WORKS_
        ON, neither Proj_No nor Emp_Id can act as the key of the table WORKS_ON (why?). However, attributes Proj_No
        and Emp_Id together form a composite key of the relation WORKS_ON. The notion of keys is described below:


               NULL: Denotes an unknown attribute value.


        9.2.2 Database keys

        1. Candidate Key

        A set of attributes that uniquely identify each tuple in a relation is called its candidate key. The set of attributes
        that form a candidate key is minimal in the sense that no subset of a candidate key qualifies to be a candidate key.
        For example, let us consider a scenario where no two projects have the same project number Proj_No. Further, the
        project names are unique within a department. However, different departments may have projects with the same
        name. Let us consider candidate keys for the relation PROJECT in this scenario. As no two projects have the same
        Proj_No, the attribute Proj_No will serve as a candidate key.


               Candidate key: Minimal set of attributes that identifies a tuple.


        As Proj_No identifies the tuples in the table PROJECT uniquely, it is evident that the following combinations of the
        attributes will also pinpoint the tuples in the table PROJECT uniquely:

        Proj_No
        Proj_No, Proj_Name

          238  Touchpad Informatics Practices-XI
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