How to get the insert ID in JDBC?

Question

I want to INSERT a record in a database (which is Microsoft SQL Server in my case) using JDBC in Java. At the same time, I want to obtain the insert ID. How can I achieve this using JDBC API?

Answer 1

If it is an auto generated key, then you can use Statement#getGeneratedKeys() for this. You need to call it on the same Statement as the one being used for the INSERT. You first need to create the statement using Statement.RETURN_GENERATED_KEYS to notify the JDBC driver to return the keys.

Here's a basic example:

public void create(User user) throws SQLException {     try (         Connection connection = dataSource.getConnection();         PreparedStatement statement = connection.prepareStatement(SQL_INSERT,                                       Statement.RETURN_GENERATED_KEYS);     ) {         statement.setString(1, user.getName());         statement.setString(2, user.getPassword());         statement.setString(3, user.getEmail());         // ...          int affectedRows = statement.executeUpdate();          if (affectedRows == 0) {             throw new SQLException("Creating user failed, no rows affected.");         }          try (ResultSet generatedKeys = statement.getGeneratedKeys()) {             if (generatedKeys.next()) {                 user.setId(generatedKeys.getLong(1));             }             else {                 throw new SQLException("Creating user failed, no ID obtained.");             }         }     } } 

Note that you're dependent on the JDBC driver as to whether it works. Currently, most of the last versions will work, but if I am correct, Oracle JDBC driver is still somewhat troublesome with this. MySQL and DB2 already supported it for ages. PostgreSQL started to support it not long ago. I can't comment about MSSQL as I've never used it.

For Oracle, you can invoke a CallableStatement with a RETURNING clause or a SELECT CURRVAL(sequencename) (or whatever DB-specific syntax to do so) directly after the INSERT in the same transaction to obtain the last generated key. See also this answer.