How to get the insert ID in JDBC?

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.

Instead of a comment, I just want to answer post.

Interface java.sql.PreparedStatement

1. columnIndexes « You can use prepareStatement function that accepts columnIndexes and SQL statement. Where columnIndexes allowed constant flags are Statement.RETURN_GENERATED_KEYS1 or Statement.NO_GENERATED_KEYS[2], SQL statement that may contain one or more '?' IN parameter placeholders.

   SYNTAX «

   Connection.prepareStatement(String sql, int autoGeneratedKeys)
   Connection.prepareStatement(String sql, int[] columnIndexes)
   

   Example:

   PreparedStatement pstmt = 
       conn.prepareStatement( insertSQL, Statement.RETURN_GENERATED_KEYS );
   

2. columnNames « List out the columnNames like 'id', 'uniqueID', .... in the target table that contain the auto-generated keys that should be returned. The driver will ignore them if the SQL statement is not an INSERT statement.

   SYNTAX «

   Connection.prepareStatement(String sql, String[] columnNames)
   

   Example:

   String columnNames[] = new String[] { "id" };
   PreparedStatement pstmt = conn.prepareStatement( insertSQL, columnNames );
   

Full Example:

public static void insertAutoIncrement_SQL(String UserName, String Language, String Message) {
    String DB_URL = "jdbc:mysql://localhost:3306/test", DB_User = "root", DB_Password = "";

    String insertSQL = "INSERT INTO `unicodeinfo`( `UserName`, `Language`, `Message`) VALUES (?,?,?)";
            //"INSERT INTO `unicodeinfo`(`id`, `UserName`, `Language`, `Message`) VALUES (?,?,?,?)";
    int primkey = 0 ;
    try {
        Class.forName("com.mysql.jdbc.Driver").newInstance();
        Connection conn = DriverManager.getConnection(DB_URL, DB_User, DB_Password);

        String columnNames[] = new String[] { "id" };

        PreparedStatement pstmt = conn.prepareStatement( insertSQL, columnNames );
        pstmt.setString(1, UserName );
        pstmt.setString(2, Language );
        pstmt.setString(3, Message );

        if (pstmt.executeUpdate() > 0) {
            // Retrieves any auto-generated keys created as a result of executing this Statement object
            java.sql.ResultSet generatedKeys = pstmt.getGeneratedKeys();
            if ( generatedKeys.next() ) {
                primkey = generatedKeys.getInt(1);
            }
        }
        System.out.println("Record updated with id = "+primkey);
    } catch (InstantiationException | IllegalAccessException | ClassNotFoundException | SQLException e) {
        e.printStackTrace();
    }
}

You can use following java code to get new inserted id.

ps = con.prepareStatement(query, Statement.RETURN_GENERATED_KEYS);
ps.setInt(1, quizid);
ps.setInt(2, userid);
ps.executeUpdate();

ResultSet rs = ps.getGeneratedKeys();
if (rs.next()) {
    lastInsertId = rs.getInt(1);
}

It is possible to use it with normal Statement's as well (not just PreparedStatement)

Statement statement = conn.createStatement();
int updateCount = statement.executeUpdate("insert into x...)", Statement.RETURN_GENERATED_KEYS);
try (ResultSet generatedKeys = statement.getGeneratedKeys()) {
  if (generatedKeys.next()) {
    return generatedKeys.getLong(1);
  }
  else {
    throw new SQLException("Creating failed, no ID obtained.");
  }
}

With Hibernate's NativeQuery, you need to return a ResultList instead of a SingleResult, because Hibernate modifies a native query

INSERT INTO bla (a,b) VALUES (2,3) RETURNING id

like

INSERT INTO bla (a,b) VALUES (2,3) RETURNING id LIMIT 1

if you try to get a single result, which causes most databases (at least PostgreSQL) to throw a syntax error. Afterwards, you may fetch the resulting id from the list (which usually contains exactly one item).

In my case ->

ConnectionClass objConnectionClass=new ConnectionClass();
con=objConnectionClass.getDataBaseConnection();
pstmtGetAdd=con.prepareStatement(SQL_INSERT_ADDRESS_QUERY,Statement.RETURN_GENERATED_KEYS);
pstmtGetAdd.setString(1, objRegisterVO.getAddress());
pstmtGetAdd.setInt(2, Integer.parseInt(objRegisterVO.getCityId()));
int addId=pstmtGetAdd.executeUpdate();              
if(addId>0)
{
    ResultSet rsVal=pstmtGetAdd.getGeneratedKeys();
    rsVal.next();
    addId=rsVal.getInt(1);
}

If you are using Spring JDBC, you can use Spring's GeneratedKeyHolder class to get the inserted ID.

See this answer... How to get inserted id using Spring Jdbctemplate.update(String sql, obj...args)

If you are using JDBC (tested with MySQL) and you just want the last inserted ID, there is an easy way to get it. The method I'm using is the following:

public static Integer insert(ConnectionImpl connection, String insertQuery){

    Integer lastInsertId = -1;
    try{
        final PreparedStatement ps = connection.prepareStatement(insertQuery);
        ps.executeUpdate(insertQuery);
        final com.mysql.jdbc.PreparedStatement psFinal = (com.mysql.jdbc.PreparedStatement) ps;
        lastInsertId = (int) psFinal.getLastInsertID();
        connection.close();
    } catch(SQLException ex){
        System.err.println("Error: "+ex);
    }

    return lastInsertId;
}

Also, (and just in case) the method to get the ConnectionImpl is the following:

public static ConnectionImpl getConnectionImpl(){
    ConnectionImpl conexion = null;

    final String dbName = "database_name";
    final String dbPort = "3306";
    final String dbIPAddress = "127.0.0.1";
    final String connectionPath = "jdbc:mysql://"+dbIPAddress+":"+dbPort+"/"+dbName+"?autoReconnect=true&useSSL=false";
    
    final String dbUser = "database_user";
    final String dbPassword = "database_password";
    try{
        conexion = (ConnectionImpl) DriverManager.getConnection(connectionPath, dbUser, dbPassword);
    }catch(SQLException e){
        System.err.println(e);
    }
    
    return conexion;
}

Remember to add the connector/J to the project referenced libraries.

In my case, the connector/J version is the 5.1.42. Maybe you will have to apply some changes to the connectionPath if you want to use a more modern version of the connector/J such as with the version 8.0.28.

In the file, remember to import the following resources:

import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import com.mysql.jdbc.ConnectionImpl;

Hope this will be helpful.

Most others have suggested to use JDBC API for this, but personally, I find it quite painful to do with most drivers. When in fact, you can just use a native T-SQL feature, the OUTPUT clause:

try (
    Statement s = c.createStatement();
    ResultSet rs = s.executeQuery(
        """
        INSERT INTO t (a, b)
        OUTPUT id
        VALUES (1, 2)
        """
    );
) {
    while (rs.next())
        System.out.println("ID = " + rs.getLong(1));
}

This is the simplest solution for SQL Server as well as a few other SQL dialects (e.g. Firebird, MariaDB, PostgreSQL, where you'd use RETURNING instead of OUTPUT).

I've blogged about this topic more in detail here.