Database Management Systems Flashcards
6 cards from real B CompE Bachelor of Computer Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Database Management Systems flashcards as text
In an Entity-Relationship (ER) diagram, what shape represents a weak entity?
Answer: Double rectangle
A weak entity is represented by a double rectangle in an ER diagram, indicating it depends on another entity for its existence.
What is denormalization in database design?
Answer: Intentionally adding redundancy to improve read performance
Denormalization intentionally introduces redundancy into a normalized database to reduce joins and speed up read-heavy queries.
Which isolation level in SQL prevents dirty reads but allows non-repeatable reads?
Answer: Read Committed
Read Committed prevents a transaction from reading uncommitted changes but allows data to change between reads within the same transaction.
What does the SQL keyword DISTINCT do in a SELECT query?
Answer: Removes duplicate rows from query results
DISTINCT eliminates duplicate rows from the result set of a SELECT query, returning only unique combinations of values.
What type of database model does MongoDB use?
Answer: Document-oriented
MongoDB is a document-oriented NoSQL database that stores data as flexible JSON-like BSON documents instead of rows in tables.
Which SQL constraint ensures that a column cannot contain NULL values?
Answer: NOT NULL
The NOT NULL constraint ensures that a column must always have a value and cannot accept NULL, enforcing data completeness.
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