Banking Computers Science Sample Paper Computer - Sample Paper - 21

  • question_answer
    Which of the following types of tables constraints will prevent the entry of duplicate rows?

    A) Primary key      

    B)        Unique

    C) Null                  

    D)        foreign key

    E) None of these

    Correct Answer: A

    Solution :

    The primary key of a relation-al table uniquely identifies each record or row in the table. For a table. It enables each record to be unique without ambiguity that is. it doesn't allow duplicate's, eg, In a table CUSTOMERS, ii is difficult to differentiate each on his name. Since homonyms may ex its. Therefore, it creates a field Code Client where each code is unique in designating it as primary key to ensure that every client is different.


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