{"id":183440,"date":"2025-01-16T13:00:06","date_gmt":"2025-01-16T13:00:06","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=183440"},"modified":"2025-01-16T13:00:08","modified_gmt":"2025-01-16T13:00:08","slug":"what-is-a-derived-attribute","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/01\/16\/what-is-a-derived-attribute\/","title":{"rendered":"What is a derived attribute"},"content":{"rendered":"\n

What is a derived attribute? Give an example. What are the advantages or disadvantages of storing or not storing a derived attribute?<\/p>\n\n\n\n

How is a relationship between entities indicated in an ERD? Give an example using<\/p>\n\n\n\n

the Crow\u2019s Foot notation.<\/p>\n\n\n\n

The Correct Answer and Explanation is :<\/strong><\/mark><\/p>\n\n\n\n

What is a Derived Attribute?<\/h3>\n\n\n\n

A derived attribute<\/strong> is an attribute that is not stored in the database but is calculated or derived from other stored attributes. For instance, in a database storing employee information, the age of an employee could be derived from their date of birth and the current date.<\/p>\n\n\n\n

Example:<\/h4>\n\n\n\n
    \n
  • Date of Birth<\/strong>: Stored attribute (e.g., 1990-01-01).<\/li>\n\n\n\n
  • Age<\/strong>: Derived attribute, calculated as the difference between the current date and the date of birth.<\/li>\n<\/ul>\n\n\n\n

    Advantages and Disadvantages of Storing Derived Attributes:<\/h4>\n\n\n\n

    Advantages of Not Storing Derived Attributes:<\/strong><\/p>\n\n\n\n

      \n
    1. Reduced Storage Requirements<\/strong>: Derived attributes do not consume additional database space.<\/li>\n\n\n\n
    2. Accuracy<\/strong>: Derived attributes are always up-to-date since they are recalculated on demand.<\/li>\n\n\n\n
    3. Consistency<\/strong>: There\u2019s no risk of mismatched data because the derived value reflects the base data.<\/li>\n<\/ol>\n\n\n\n

      Disadvantages of Not Storing Derived Attributes:<\/strong><\/p>\n\n\n\n

        \n
      1. Increased Computation<\/strong>: Calculating derived attributes each time they are accessed can affect performance.<\/li>\n\n\n\n
      2. Complex Queries<\/strong>: Queries may become more complex, as calculations need to be included in every query requiring the derived attribute.<\/li>\n<\/ol>\n\n\n\n

        Advantages of Storing Derived Attributes:<\/strong><\/p>\n\n\n\n

          \n
        1. Faster Access<\/strong>: Storing derived attributes allows quicker retrieval since no calculations are needed.<\/li>\n\n\n\n
        2. Simpler Queries<\/strong>: Derived values are precomputed, making queries easier to write.<\/li>\n<\/ol>\n\n\n\n

          Disadvantages of Storing Derived Attributes:<\/strong><\/p>\n\n\n\n

            \n
          1. Inconsistencies<\/strong>: If the base data changes, the derived attribute may not automatically update.<\/li>\n\n\n\n
          2. Increased Storage<\/strong>: Storing derived attributes requires additional space.<\/li>\n<\/ol>\n\n\n\n
            \n\n\n\n

            Indicating Relationships in an ERD Using Crow\u2019s Foot Notation<\/h3>\n\n\n\n

            In an Entity-Relationship Diagram (ERD), relationships between entities are represented using lines and specific symbols. In Crow\u2019s Foot Notation<\/strong>, relationships are depicted with symbols like:<\/p>\n\n\n\n

              \n
            • Lines<\/strong> to connect entities.<\/li>\n\n\n\n
            • Crow\u2019s Foot (three prongs)<\/strong> for “many.”<\/li>\n\n\n\n
            • Straight line<\/strong> for “one.”<\/li>\n\n\n\n
            • Circle<\/strong> for optional participation.<\/li>\n<\/ul>\n\n\n\n

              Example:<\/h4>\n\n\n\n
                \n
              • Entities<\/strong>: Customer<\/code> and Order<\/code>.<\/li>\n\n\n\n
              • Relationship<\/strong>: A customer can place multiple orders, and each order belongs to one customer.<\/li>\n<\/ul>\n\n\n\n

                Using Crow\u2019s Foot:<\/p>\n\n\n\n

                  \n
                • The line between Customer<\/code> and Order<\/code> would show:<\/li>\n\n\n\n
                • A single line<\/strong> at the Customer<\/code> side (indicating “one”).<\/li>\n\n\n\n
                • A crow\u2019s foot<\/strong> at the Order<\/code> side (indicating “many”).<\/li>\n<\/ul>\n\n\n\n

                  This relationship can be read as:<\/p>\n\n\n\n

                    \n
                  • “A customer can place zero or many orders.”<\/li>\n\n\n\n
                  • “An order belongs to exactly one customer.”<\/li>\n<\/ul>\n\n\n\n

                    Crow\u2019s Foot Notation is widely used for its simplicity in representing cardinality and participation clearly.<\/p>\n","protected":false},"excerpt":{"rendered":"

                    What is a derived attribute? Give an example. What are the advantages or disadvantages of storing or not storing a derived attribute? How is a relationship between entities indicated in an ERD? Give an example using the Crow\u2019s Foot notation. The Correct Answer and Explanation is : What is a Derived Attribute? A derived attribute […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-183440","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/183440","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=183440"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/183440\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=183440"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=183440"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=183440"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}