JDBC Transaction in Java: Commit, Rollback, and Savepoint Explained with Flowchart

JDBC Transaction in Java

A JDBC transaction is a set of SQL operations executed as a single atomic unit.

All the SQL queries inside a transaction must either succeed together or fail together. If any query fails, the entire transaction is rolled back to maintain data consistency.

🔹 Key Concepts

Transaction Success:

• All SQL queries in the transaction execute successfully → Commit the transaction.

Transaction Failure:

• If any SQL query fails → Rollback the entire transaction.

3. Auto-Commit Mode:

• By default, JDBC connections run in auto-commit mode.
• In auto-commit mode, each SQL query is committed immediately after execution.

4. Manual Transaction Control:

To manage transactions manually:

connection.setAutoCommit(false); // Disable auto-commit

• true → Enable auto-commit
• false → Disable auto-commit

🔹 Commit & Rollback Methods

            Method.                          Purpose.                                                 Provided By

• commit().   Saves all SQL queries executed in the transaction.    Connection interface (DB vendor implementation)
• rollback().          Reverts all changes made in the transaction.       Connection interface
• rollback(Savepoint savepoint).   Reverts changes up to a specific save point.  Connection interface
• setSavepoint().   Creates a savepoint for partial rollback.   Connection interface

🔹 Flow of JDBC Transaction

/* Transaction Start */

try {

    // SQL Query 1

    // SQL Query 2

    // SQL Query 3

    

    // If all queries execute successfully

    connection.commit();

} catch (SQLException e) {

    // Rollback entire transaction if any query fails

    connection.rollback();

}

/* Transaction End */

Explanation:

• Disable auto-commit mode.
• Execute multiple SQL queries.
• If all queries succeed → commit() saves changes.
• If any query fails → rollback() restores the database to its previous state.

🔹 Real-Life Example

       Bank Transfer Scenario:

• SQL Query 1 → Deduct amount from Account A
• SQL Query 2 → Add amount to Account B
• If both succeed → Commit transaction
• If any fails → Rollback entire transfer to prevent data inconsistency