DBMS-Introduction to Database Design Questions and Answers

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Q31
What is the purpose of GROUP BY clause?
  • A Group rows with same values
  • B Sort data alphabetically
  • C Filter records
  • D Join tables
Answer: Option A
Explanation: GROUP BY groups rows that have same values into summary rows, typically used with aggregate functions.
Q32
Which data type stores date and time?
  • A DATETIME
  • B STRING
  • C INTEGER
  • D BOOLEAN
Answer: Option A
Explanation: DATETIME data type stores both date and time information in databases.
Q33
What is a candidate key?
  • A Potential primary key
  • B Foreign key reference
  • C Temporary key
  • D Encryption key
Answer: Option A
Explanation: A candidate key is a column or set of columns that can uniquely identify a record and could be chosen as primary key.
Q34
Which SQL command removes a table?
  • A DROP TABLE
  • B DELETE TABLE
  • C REMOVE TABLE
  • D ERASE TABLE
Answer: Option A
Explanation: DROP TABLE command permanently deletes a table and all its data from the database.
Q35
What is data warehousing?
  • A Business intelligence data collection
  • B Real-time transaction processing
  • C Data encryption
  • D User authentication
Answer: Option A
Explanation: Data warehousing involves collecting and managing data from various sources for business intelligence and reporting.
Q36
Which join returns all records from both tables?
  • A FULL OUTER JOIN
  • B INNER JOIN
  • C LEFT JOIN
  • D RIGHT JOIN
Answer: Option A
Explanation: FULL OUTER JOIN returns all records when there is a match in either left or right table.
Q37
What is database cursor?
  • A Row-by-row result processing
  • B Database backup tool
  • C User authentication method
  • D Data encryption technique
Answer: Option A
Explanation: A cursor is a database object used to retrieve, manipulate, and navigate through result sets row by row.
Q38
Which constraint ensures unique values?
  • A UNIQUE
  • B PRIMARY KEY
  • C FOREIGN KEY
  • D NOT NULL
Answer: Option A
Explanation: UNIQUE constraint ensures all values in a column are different from each other.
Q39
What is deadlock in databases?
  • A Mutual blocking of transactions
  • B Fast data retrieval
  • C Data encryption process
  • D Backup procedure
Answer: Option A
Explanation: Deadlock occurs when two or more transactions are waiting for each other to release locks, causing permanent blocking.
Q40
Which SQL command adds new records?
  • A INSERT
  • B ADD
  • C CREATE
  • D NEW
Answer: Option A
Explanation: INSERT command is used to add new records to a database table.

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