Database Transactions Quiz

What is a Transaction?

• A database index

• A logical unit of work that contains one or more SQL statements

• A single SQL statement

• A database schema

Answer explanation

A Transaction is a logical unit of work that contains one or more SQL statements, making it the correct choice among the options provided.

When does a transaction end?

• When a DDL statement is issued

• When a DML statement is executed

• When it is committed or rolled back

• When a SELECT statement is executed

Answer explanation

A transaction ends when it is committed or rolled back, indicating the finality of the changes made within the transaction.

What does the ACID model stand for in database transactions?

• Atomicity, Consistency, Isolation, Durability

• Agility, Consistency, Isolation, Durability

• Accuracy, Consistency, Isolation, Durability

• Atomicity, Consistency, Integrity, Durability

Answer explanation

The correct choice is Atomicity, Consistency, Isolation, Durability, which are the key principles of the ACID model in database transactions.

Which SQL statement is used to commit a transaction?

• SAVEPOINT

• LOCK TABLES

• ROLLBACK

• COMMIT

Answer explanation

The SQL statement used to commit a transaction is COMMIT, which finalizes the changes made during the transaction.

What does the ROLLBACK TO SAVEPOINT statement do?

• Rolls back the transaction to a specific savepoint

• Locks the tables

• Commits the transaction

• Releases all savepoints

Answer explanation

The ROLLBACK TO SAVEPOINT statement rolls back the transaction to a specific savepoint, undoing changes made after that point.

What is the purpose of LOCK TABLES in MySQL?

• To commit a transaction

• To unlock tables

• To acquire table locks for the current session

• To release table locks

Answer explanation

The purpose of LOCK TABLES in MySQL is to acquire table locks for the current session, allowing exclusive access to the specified tables.

Which keyword makes a SET TRANSACTION statement apply globally for all subsequent sessions?

• GLOBAL

• TRANSACTION

• ISOLATION LEVEL

• SESSION

Answer explanation

The keyword 'GLOBAL' makes a SET TRANSACTION statement apply globally for all subsequent sessions, ensuring it affects all sessions.

What is the purpose of the BEGIN statement in MySQL transactions?

• To lock tables

• To end the transaction

• To release savepoints

• To begin a new transaction

Answer explanation

The BEGIN statement in MySQL transactions is used to begin a new transaction, not to lock tables, end the transaction, or release savepoints.

Which isolation level ensures that a transaction sees only committed data?

• SERIALIZABLE

• READ UNCOMMITTED

• READ COMMITTED

• REPEATABLE READ

Answer explanation

READ COMMITTED isolation level ensures that a transaction sees only committed data, making it the correct choice.

What does the RELEASE SAVEPOINT statement do?

• Locks the tables

• Commits the transaction

• Releases a savepoint

• Rolls back to a savepoint

Answer explanation

The RELEASE SAVEPOINT statement releases a savepoint in a transaction, allowing you to roll back to that point if needed.