Database [3i Infotech Placement]: Sample Questions 95 - 96 of 294

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Question 95

Database

Question

MCQ▾

In mapping of ERD to DFD

Choices

Choice (4)

a.

Relations in ERD has 1 to 1 correspondence to processes in DFD

b.

Entities in ERD should correspond to an existing entity/store in DFD

c.

Relationships in ERD has 1 to 1 correspondence to flows in DFD

d.

Entity in DFD is converted to attributes of an entity in ERD

Answer

b.

Explanation

  • DFD- Data Flow Diagram- shows how data enters a system, are transformed in that system, and how it is stored in it.
  • ERD - Entity Representation Diagram- represents the entity model and will show what a system or a database will look like but not explain how to implement it.
  • Entities in ERD should correspond to an existing entity/store in DFD.

ERD

  • ERD is a snapshot of data structures.
  • Shows entities (tables) in a database and relationships between tables within that database.
  • For a good database design it is essential to have an ERD.

DFD

  • DFD is a graphical representation of the “flow” of data through an information system.
  • It views a system as a function that transforms the input into desired output.

Question 96

Database
Edit

Describe in Detail

Essay▾

What are the privileges that can be granted on a table by a user to others?

Explanation

  • User requires ADMIN privilege to grant privileges to others. For example:
    • Delete:
      • Delete rows from tables within the schema.
    • Insert:
      • Insert rows of data into tables within the schema.
  • References:
    • Set up references to primary keys within the schema.
  • Select:
    • To select rows from tables within the schema.
  • Trigger:
    • To create triggers on tables within the schema.
  • Update:
    • Update rows in tables within the shaman.
  • Execute:
    • Execute functions or stored procedure within the shaman.

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