Database-MySQL [3i Infotech Placement]: Sample Questions 96 - 97 of 162

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Question 96

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Write in Short

Short Answer▾

What is Relationship?

Explanation

  • A relationship is an association between several entities.
  • A relationship, in the context of databases, is a situation that exists between two relational database tables when one table has a foreign key that references the primary key of the other table.
  • Relationships allow relational databases to split and store data in different tables, while linking disparate data items.

Question 97

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Describe in Detail

Essay▾

What is Multivalued dependency?

Explanation

Define Multivalued Dependancy
  • Multivalued dependency occurs when there are more than one independent multivalued attributes in a table.
  • For example:
    • Consider a bike manufacture company, which produces two colors (Black and white) in each model every year.
    Table Shows the Bike Manufacture Company
    Bike_modelManuf_yearcolor
    M012008Black
    M012008Red
    M022011Black
    M022011Red
    M202015Black
    M202015Red
  • Columns manuf_year and color are independent of each other and dependent on bike_model. In this case these two columns are said to be multivalued dependent on bike_model.
  • These dependencies can be represented like this:

bike_model ⇾ manuf_year

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