Java Programming — MCQ Practice Questions & Answers

Question 1

What does the executeUpdate() method return in JDBC?

Accepted Answer

Correct answer: B. Number of rows affected — executeUpdate() returns an integer representing the number of rows affected by INSERT, UPDATE, or DELETE operations. executeQuery() returns ResultSet.

Answer

A. A ResultSet object

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C. A boolean value

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D. Query execution time

Question 2

Which interface is used to execute precompiled SQL statements in JDBC?

Accepted Answer

Correct answer: B. PreparedStatement — PreparedStatement is used for precompiled SQL statements with parameters. It provides better performance and prevents SQL injection compared to Statement.

Answer

A. Statement

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C. CallableStatement

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D. BatchStatement

Question 3

What is the primary advantage of using PreparedStatement over Statement?

Accepted Answer

Correct answer: A. Faster execution and SQL injection prevention — PreparedStatement offers faster execution due to precompilation and prevents SQL injection through parameterized queries using placeholders (?).

Answer

B. Larger result set size

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C. Better memory management

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D. Automatic type conversion

Question 4

Which method must be called to move cursor to the next row in ResultSet?

Accepted Answer

Correct answer: A. next() — The next() method moves the ResultSet cursor to the next row and returns true if a row exists, false if no more rows. It's essential for iterating through results.

Answer

B. moveNext()

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C. advance()

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D. fetch()

Question 5

What is Connection pooling in JDBC?

Accepted Answer

Correct answer: A. Storing multiple database connections in a pool for reuse — Connection pooling maintains a pool of reusable database connections to improve performance and reduce overhead of creating new connections repeatedly.

Answer

B. Combining multiple queries into one

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C. Creating backup connections

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D. Automatic connection switching

Question 6

Which DriverManager method is used to establish a database connection?

Accepted Answer

Correct answer: B. getConnection() — DriverManager.getConnection() is the standard method that takes URL, username, and password to establish a connection to the database.

Answer

A. createConnection()

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C. establishConnection()

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D. openConnection()

Question 7

What does the setAutoCommit(false) method do in JDBC?

Accepted Answer

Correct answer: A. Disables automatic transaction commit — setAutoCommit(false) disables automatic commit, allowing multiple statements to be part of single transaction. Manual commit() or rollback() must be called.

Answer

B. Enables automatic transaction commit

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C. Rolls back current transaction

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D. Closes the connection

Question 8

Which of the following is the correct way to close JDBC resources to prevent resource leaks?

Accepted Answer

Correct answer: D. Both A and C are correct — Resources should be closed in reverse order of creation (ResultSet → Statement → Connection), or preferably using try-with-resources which auto-closes resources.

Answer

A. Close ResultSet, Statement, then Connection

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B. Close Connection only

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C. Use try-with-resources statement

Java Programming - MCQ Practice Questions