Top 20 JDBC Interview Questions and Answers

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JDBC stands for Java Database Connectivity. It was introduced by Sun Microsystems in 1997 as a way for Java applications to connect with databases. James Gosling, who also created Java, played a key role in its development. JDBC is used to send SQL queries, update records, and manage database connections in Java-based systems. It is a must-know for roles like Java developer, backend engineer, and software programmer. In this blog, we have listed the top 20 JDBC interview questions and answers to help you prepare and increase your chances in technical interviews.

Fun Fact: The name “JDBC” was inspired by ODBC (Open Database Connectivity), a Microsoft technology. Sun Microsystems wanted something similar for Java, and that’s how JDBC was born.

JDBC Interview Questions for Freshers

Here are some commonly asked interview questions on JDBC in Java for freshers and entry-level professionals. 

1. What is JDBC and how does it work in a Java application?

JDBC stands for Java Database Connectivity. It is an API that lets Java applications talk to databases using SQL. When I write Java code to connect with a database, JDBC handles the connection, query execution, and result fetching.

2. What are the steps to connect a Java application to a database using JDBC?

First, I load the database driver. Then I use DriverManager.getConnection() to connect. After that, I create a Statement or PreparedStatement to run SQL. I process the ResultSet and finally close everything.

3. What is the role of the DriverManager class in JDBC?

DriverManager manages JDBC drivers and helps create a connection between Java code and the database. It picks the right driver based on the JDBC URL passed to it.

4. Explain the difference between Statement, PreparedStatement, and CallableStatement.

Statement is used for running simple SQL. PreparedStatement lets me run parameterized queries and is safer against SQL injection. CallableStatement is for executing stored procedures in the database.

5. What is the ResultSet interface and how do you use it to retrieve data?

ResultSet holds data returned after running a SELECT query. I use next() to move through rows and getXXX() methods like getInt() or getString() to read column values.

6. What are the different types of JDBC drivers?

There are four types:

• Type 1: JDBC-ODBC Bridge
• Type 2: Native-API
• Type 3: Network Protocol
• Type 4: Thin Driver (most used today)

7. What is the use of Class.forName() in JDBC?

Before Java 6, I had to use Class.forName() to load the JDBC driver class. It registers the driver with DriverManager. Since JDBC 4.0, it is optional if the driver JAR is in the classpath.

JDBC Interview Questions for Experienced Professionals

Let’s go through some advanced JDBC in Java interview questions that are often asked in senior-level technical interviews.

8. What is connection pooling and how does it improve database access?

Connection pooling keeps a set of database connections ready to use. Instead of opening a new connection every time, the app reuses one from the pool. This saves time and reduces load on the database.

9. How do you manage transactions manually using JDBC?

I turn off auto-commit using setAutoCommit(false). Then I execute all my SQL statements. If everything works, I call commit(). If anything fails, I use rollback() to undo changes. 

10. What are the different transaction isolation levels in JDBC and when would you use each?

JDBC supports five levels:

• TRANSACTION_READ_UNCOMMITTED – fastest, but allows dirty reads.
• TRANSACTION_READ_COMMITTED – blocks dirty reads.
• TRANSACTION_REPEATABLE_READ – avoids dirty and non-repeatable reads.
• TRANSACTION_SERIALIZABLE – strictest, fully isolates transactions.
• TRANSACTION_NONE – no transaction control.

I choose based on how critical the data accuracy is.

11. How do you handle batch processing in JDBC and what are its benefits?

I add queries using addBatch() and run them with executeBatch(). This reduces round trips to the database and boosts performance during bulk inserts or updates.

12. What is the difference between optimistic and pessimistic locking in JDBC?

Optimistic locking assumes no conflicts and only checks at update time. Pessimistic locking locks the row early, avoiding changes by others while I update it.

13. What is a two-phase commit and how is it implemented in JDBC?

It is used in distributed transactions. First, all resources prepare to commit. If all agree, the second phase commits. If any fail, it rolls back everything.

14. How do you use DatabaseMetaData and ResultSetMetaData in JDBC?

DatabaseMetaData gives info about the database like name, version, and tables. ResultSetMetaData gives details about columns in the result like names and types. I use both to write dynamic JDBC code.

Also Read - Top 15+ Advanced Java Interview Questions

JDBC Programming Questions

Here are practical JDBC programming questions to test your hands-on skills and problem-solving in Java.

15. Write a Java program to insert a record into a database using PreparedStatement.

Connection conn = DriverManager.getConnection(url, user, pass);

String sql = “INSERT INTO employee (id, name) VALUES (?, ?)”;

PreparedStatement ps = conn.prepareStatement(sql);

ps.setInt(1, 101);

ps.setString(2, “John”);

ps.executeUpdate();

ps.close();

conn.close();

16. How would you fetch records from a table and display them using ResultSet?

Connection conn = DriverManager.getConnection(url, user, pass);

Statement stmt = conn.createStatement();

ResultSet rs = stmt.executeQuery(“SELECT * FROM employee”);

while (rs.next()) {

    int id = rs.getInt(“id”);

    String name = rs.getString(“name”);

    System.out.println(id + ” – ” + name);

}

rs.close();

stmt.close();

conn.close();

17. Demonstrate how to call a stored procedure using CallableStatement.

Connection conn = DriverManager.getConnection(url, user, pass);

CallableStatement cs = conn.prepareCall(“{call getEmployeeName(?, ?)}”);

cs.setInt(1, 101);

cs.registerOutParameter(2, Types.VARCHAR);

cs.execute();

String name = cs.getString(2);

System.out.println(“Employee Name: ” + name);

cs.close();

conn.close();

18. Write code to perform batch insert using addBatch() and executeBatch().

Connection conn = DriverManager.getConnection(url, user, pass);

String sql = “INSERT INTO employee (id, name) VALUES (?, ?)”;

PreparedStatement ps = conn.prepareStatement(sql);

for (int i = 1; i <= 5; i++) {

    ps.setInt(1, 100 + i);

    ps.setString(2, “Emp” + i);

    ps.addBatch();

}

ps.executeBatch();

ps.close();

conn.close();

19. Show how to handle exceptions and rollback in JDBC transactions.

Connection conn = DriverManager.getConnection(url, user, pass);

try {

    conn.setAutoCommit(false);

    Statement stmt = conn.createStatement();

    stmt.executeUpdate(“UPDATE employee SET name=’Alex’ WHERE id=101”);

    stmt.executeUpdate(“INSERT INTO logs (message) VALUES (‘Update done’)”);

    conn.commit();

} catch (SQLException e) {

    conn.rollback();

    e.printStackTrace();

} finally {

    conn.close();

}

20. Write a program to dynamically create a table using JDBC.

Connection conn = DriverManager.getConnection(url, user, pass);

Statement stmt = conn.createStatement();

String tableName = “new_employee”;

String sql = “CREATE TABLE ” + tableName + ” (id INT, name VARCHAR(100))”;

stmt.executeUpdate(sql);

System.out.println(“Table created: ” + tableName);

stmt.close();

conn.close();

How to Prepare for JDBC Interview?

Preparing for a JDBC interview means knowing both concepts and code used in real-world Java projects. Follow these tips to prepare: 

• Understand JDBC architecture and components like DriverManager, Connection, and ResultSet
• Practice writing code using PreparedStatement, CallableStatement, and batch operations
• Know how to manage transactions and handle exceptions
• Review common JDBC interview questions from recent years
• Learn how JDBC is used in Spring and enterprise apps
• Keep examples ready from your own experience or practice projects

Also Read - Top 20+ Microservices Architecture Interview Questions and Answers

Wrapping Up

And that’s a wrap on the 20 most important JDBC interview questions and answers. These will help you feel more confident in technical interviews and refresh your Java database skills. Practice coding and understand the concepts well.

Looking for JDBC jobs? Head over to Hirist, where you can find top IT job openings today.

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