Computer Science: DBMS Concepts Flashcards
6 cards from real AMCAT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Computer Science: DBMS Concepts flashcards as text
What is a deadlock in a database system?
Answer: Two or more transactions waiting indefinitely for each other's locked resources
Deadlock occurs when transactions each hold a resource the other needs, creating a circular wait.
Which SQL command removes a table and all its data permanently?
Answer: DROP
DROP TABLE removes the table structure and all data permanently. DELETE removes rows. TRUNCATE removes all rows but keeps structure.
In the Entity-Relationship model, what does a diamond shape represent?
Answer: Relationship
In ER diagrams: rectangles = entities, diamonds = relationships, ellipses = attributes.
What is denormalization?
Answer: Adding redundancy to improve read performance
Denormalization intentionally introduces redundancy to improve read query performance.
Which transaction isolation level prevents dirty reads but allows non-repeatable reads?
Answer: READ COMMITTED
READ COMMITTED prevents dirty reads but allows non-repeatable reads (another transaction may modify data between two reads in the same transaction).
What is a view in SQL?
Answer: A virtual table defined by a query
A view is a virtual table whose contents are defined by a SQL query. It does not store data itself.