DBMS-Introduction to Database Design Questions and Answers

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Q21
What is a composite key?
  • A Multiple column key
  • B Single column key
  • C Encrypted key
  • D Temporary key
Answer: Option A
Explanation: A composite key consists of two or more columns that uniquely identify a record in a table.
Q22
Which SQL command modifies existing data?
  • A UPDATE
  • B MODIFY
  • C CHANGE
  • D ALTER
Answer: Option A
Explanation: UPDATE command is used to modify existing records in a database table.
Q23
What is the purpose of an index?
  • A Faster data retrieval
  • B Data encryption
  • C Data compression
  • D Data backup
Answer: Option A
Explanation: Indexes improve query performance by providing faster data retrieval through optimized search paths.
Q24
Which database model uses parent-child relationships?
  • A Hierarchical model
  • B Relational model
  • C Network model
  • D Object model
Answer: Option A
Explanation: Hierarchical model organizes data in tree-like structures with parent-child relationships.
Q25
What is data dictionary?
  • A Database metadata
  • B User data
  • C Backup data
  • D Temporary data
Answer: Option A
Explanation: Data dictionary contains metadata about database structure, tables, columns, and relationships.
Q26
Which constraint maintains referential integrity?
  • A Foreign key
  • B Primary key
  • C Unique key
  • D Check constraint
Answer: Option A
Explanation: Foreign key constraint ensures referential integrity between related tables.
Q27
What is a weak entity?
  • A Depends on another entity
  • B Strong independent entity
  • C Temporary entity
  • D Virtual entity
Answer: Option A
Explanation: A weak entity depends on another entity for its existence and identification.
Q28
Which SQL function counts records?
  • A COUNT()
  • B TOTAL()
  • C SUM()
  • D CALCULATE()
Answer: Option A
Explanation: COUNT() function returns the number of records matching specified criteria.
Q29
What is database schema?
  • A Logical database structure
  • B Physical storage
  • C User interface
  • D Network configuration
Answer: Option A
Explanation: Database schema defines the logical structure and organization of the database.
Q30
Which normal form requires elimination of partial dependencies?
  • A Second Normal Form
  • B First Normal Form
  • C Third Normal Form
  • D Fourth Normal Form
Answer: Option A
Explanation: Second Normal Form (2NF) eliminates partial dependencies where attributes depend on part of a composite key.

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