How to Retrieve Auto-Generated IDs After an INSERT Operation in JDBC?

Getting the Auto-Generated ID After an INSERT in JDBC

In JDBC, retrieving the ID generated by an INSERT statement is essential, particularly when using auto-incrementing keys or sequences. This guide outlines several methods to achieve this.

Using Statement.RETURN_GENERATED_KEYS:

The most straightforward approach leverages JDBC's Statement.RETURN_GENERATED_KEYS flag. When used with PreparedStatement or CallableStatement, this instructs the driver to return the newly generated keys.

Example:

<code class="language-java">PreparedStatement statement = connection.prepareStatement(SQL_INSERT, Statement.RETURN_GENERATED_KEYS);
// ... execute the INSERT statement ...

ResultSet generatedKeys = statement.getGeneratedKeys();
if (generatedKeys.next()) {
    long insertId = generatedKeys.getLong(1); // Get the first generated key
}</code>

Database-Specific Solutions:

If RETURN_GENERATED_KEYS isn't supported by your database or driver, database-specific queries are needed:

• Oracle: Employ a CallableStatement with a RETURNING clause, or execute a SELECT CURRVAL(sequencename) query after the INSERT.
• MySQL: Use SELECT LAST_INSERT_ID() to retrieve the most recently inserted ID.

JDBC Driver Compatibility:

Remember that support for RETURN_GENERATED_KEYS can vary across JDBC drivers. Consult your driver's documentation to confirm its capabilities. Older drivers might require alternative methods.

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