Java Programming — JDBC Questions & Answers

Q.1 Hard JDBC

In JDBC metadata operations, which method is used to retrieve information about table structure, column names, and their data types?

A getDatabaseMetaData()

B getMetaData() on ResultSet

C getColumnCount() and getColumnName()

D Both B and C together

Correct Answer: D. Both B and C together

EXPLANATION

getMetaData() on ResultSet returns ResultSetMetaData which provides column information. getColumnCount() and getColumnName() are methods of ResultSetMetaData used to retrieve structure details.

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Q.2 Hard JDBC

A Java application requires connection pooling to handle 1000+ concurrent database requests efficiently. Which JDBC component should be implemented?

A Direct DriverManager.getConnection() calls

B DataSource interface with connection pool implementation like HikariCP or C3P0

C Creating new Connection for each request manually

D Using Statement caching only

Correct Answer: B. DataSource interface with connection pool implementation like HikariCP or C3P0

EXPLANATION

DataSource with connection pooling frameworks (HikariCP, C3P0) efficiently manages connections by reusing them, reducing overhead. Direct getConnection() calls create new connections each time, which is inefficient for high concurrency.

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Q.3 Hard JDBC

In a JDBC application using batch updates, what happens if one statement in the batch fails?

A All statements are executed, and failure is reported

B All statements are rolled back automatically

C Only failed statement is skipped

D Behavior depends on database configuration

Correct Answer: D. Behavior depends on database configuration

EXPLANATION

executeBatch() behavior on failure varies by database and driver. BatchUpdateException is thrown, containing update counts for each statement. Explicit transaction control is recommended.

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Q.4 Hard JDBC

A query execution takes 5 seconds consistently. Which JDBC optimization technique should NOT be used for this scenario?

A Connection pooling

B Batch processing for multiple inserts

C Using indexes on frequently queried columns

D Increasing setFetchSize() value

Correct Answer: D. Increasing setFetchSize() value

EXPLANATION

If query execution itself is slow (5 seconds), the bottleneck is in database operations, not data transfer. Increasing setFetchSize() only optimizes data retrieval, not query execution.

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Q.5 Hard JDBC

A developer wants to retrieve data from a stored procedure that returns multiple result sets and output parameters. Which approach is correct?

A Use Statement with executeQuery()

B Use PreparedStatement with execute()

C Use CallableStatement with registerOutParameter() and execute()

D Use PreparedStatement with setFetchSize()

Correct Answer: C. Use CallableStatement with registerOutParameter() and execute()

EXPLANATION

CallableStatement is specifically designed for stored procedures, supporting registerOutParameter() for output parameters and getMoreResults() for multiple result sets.

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Q.6 Hard JDBC

When using JDBC with Spring Framework in 2024-25, which approach is recommended for resource management?

A Manual try-catch blocks

B Try-with-resources statement

C JdbcTemplate with Spring

D DriverManager only

Correct Answer: C. JdbcTemplate with Spring

EXPLANATION

JdbcTemplate in Spring Framework automatically manages JDBC resources and is the recommended approach in modern applications.

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Q.7 Hard JDBC

In JDBC, what is the significance of setting FetchSize on a Statement when dealing with large ResultSets?

A It determines the maximum number of rows to fetch from database in one round-trip

B It sets the total memory allocated for ResultSet

C It automatically closes the ResultSet

D It enables caching of all rows in memory

Correct Answer: A. It determines the maximum number of rows to fetch from database in one round-trip

EXPLANATION

FetchSize controls how many rows are fetched from the database at once, optimizing performance for large datasets.

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Q.8 Hard JDBC

Which JDBC feature should be used for executing multiple SQL statements in a batch for optimal performance?

A executeUpdate() in a loop

B executeBatch() with addBatch()

C execute() method

D Multiple Statement objects

Correct Answer: B. executeBatch() with addBatch()

EXPLANATION

executeBatch() with addBatch() reduces network round-trips and improves performance for bulk operations.

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Q.9 Hard JDBC

In a JDBC application, when using transactions with setAutoCommit(false), what happens to intermediate savepoints if rollback() is called?

A All changes are saved

B Only savepoint changes are rolled back

C All changes since last commit are rolled back

D The entire connection is closed

Correct Answer: C. All changes since last commit are rolled back

EXPLANATION

When rollback() is called without savepoints, all changes made since the last commit are undone and rolled back.

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Q.10 Hard JDBC

Consider a scenario: A developer uses Statement with user input directly in SQL queries. What is the primary risk?

A Slower query execution

B SQL Injection attacks

C Memory leaks

D Connection timeout

Correct Answer: B. SQL Injection attacks

EXPLANATION

Direct concatenation of user input in SQL queries exposes the application to SQL injection attacks. PreparedStatement should be used instead.

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