Java Programming — JDBC Questions & Answers

Q.81 Easy JDBC

What is the correct syntax to retrieve an integer value from a ResultSet object at column index 2?

A rs.getInt(2);

B rs.getInteger(2);

C rs.fetchInt(2);

D rs.readInt(2);

Correct Answer: A. rs.getInt(2);

EXPLANATION

The correct method is getInt(int columnIndex) which retrieves an integer value from the ResultSet at the specified column index (1-based indexing).

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Q.82 Easy JDBC

Which JDBC driver type is platform-independent and does not require native code installation?

A Type 1 Driver

B Type 2 Driver

C Type 3 Driver

D Type 4 Driver

Correct Answer: D. Type 4 Driver

EXPLANATION

Type 4 drivers (thin drivers) are pure Java drivers that communicate directly with the database using the database native protocol. They are platform-independent and do not require native code.

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Q.83 Medium JDBC

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

A Close ResultSet, Statement, then Connection

B Close Connection only

C Use try-with-resources statement

D Both A and C are correct

Correct Answer: D. Both A and C are correct

EXPLANATION

Resources should be closed in reverse order of creation (ResultSet → Statement → Connection), or preferably using try-with-resources which auto-closes resources.

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Q.84 Hard JDBC

In JDBC, what does the ResultSet.TYPE_SCROLL_INSENSITIVE constant represent?

A Non-scrollable result set

B Scrollable result set that doesn't reflect database changes

C Forward-only result set

D Bidirectional result set

Correct Answer: B. Scrollable result set that doesn't reflect database changes

EXPLANATION

TYPE_SCROLL_INSENSITIVE creates scrollable ResultSet (can move forward/backward) but changes made to database after ResultSet creation are not reflected.

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Q.85 Hard JDBC

Which JDBC feature allows you to call stored procedures?

A Statement

B PreparedStatement

C CallableStatement

D ExecutableStatement

Correct Answer: C. CallableStatement

EXPLANATION

CallableStatement is used to invoke stored procedures and functions. It extends PreparedStatement and supports IN, OUT, and INOUT parameters.

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Q.86 Hard JDBC

What is the difference between execute(), executeQuery(), and executeUpdate()?

A execute() returns boolean, executeQuery() returns ResultSet, executeUpdate() returns int

B All three are identical

C execute() is fastest, others are slower

D executeQuery() updates database, executeUpdate() retrieves data

Correct Answer: A. execute() returns boolean, executeQuery() returns ResultSet, executeUpdate() returns int

EXPLANATION

execute() returns boolean (true if ResultSet available), executeQuery() returns ResultSet for SELECT, executeUpdate() returns row count for INSERT/UPDATE/DELETE.

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Q.87 Hard JDBC

How would you implement batch processing in JDBC for multiple INSERT operations?

A Use addBatch() and executeBatch() methods

B Execute each insert in a loop separately

C Use multiple connections

D Create multiple statements

Correct Answer: A. Use addBatch() and executeBatch() methods

EXPLANATION

addBatch() adds SQL command to batch, executeBatch() executes all batched commands at once, improving performance significantly for multiple operations.

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Q.88 Hard JDBC

Consider code: String query = "SELECT * FROM users WHERE id=" + userId; stmt.executeQuery(query); What security issue exists?

A Performance degradation

B SQL Injection vulnerability

C Memory leak

D Connection timeout

Correct Answer: B. SQL Injection vulnerability

EXPLANATION

This is vulnerable to SQL injection as user input is directly concatenated. Using PreparedStatement with parameters prevents this: "SELECT * FROM users WHERE id=?"

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Q.89 Medium JDBC

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

A Disables automatic transaction commit

B Enables automatic transaction commit

C Rolls back current transaction

D Closes the connection

Correct Answer: A. Disables automatic transaction commit

EXPLANATION

setAutoCommit(false) disables automatic commit, allowing multiple statements to be part of single transaction. Manual commit() or rollback() must be called.

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Q.90 Medium JDBC

Which DriverManager method is used to establish a database connection?

A createConnection()

B getConnection()

C establishConnection()

D openConnection()

Correct Answer: B. getConnection()

EXPLANATION

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

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