Re: concurrency problem

Locks are released when the containing transaction
commits. There is no explicit "release."

Instead of calling "begin" and "commit" as statements,
I do something more like below. As Aaron mentioned,
this is JDBC, not SQL. Sorry people.

try {
...
conn.setAutoCommit(false);

    //do the insert on the table that generates the
primary key via a sequence
    PreparedStatement pstmt =
conn.prepareStatement ("my prepared statement");
    pstmt.executeUpdate();

    //your prepared statement above should do an
    //insert on a table that calls nextval().
    //Calling currval() below will guarantee that
you'll get
    //the value created by the insert statement
    //Check out the documentation on sequence
functions

    //get the new primary key
    String get_pkey = "{ ? = call currval('my_seq')
}";
    CallableStatement = conn.prepareCall(get_pkey);
    cstmt.registerOutParameter(1, Types.BIGINT);
    cstmt.execute();

    long new_pkey = cstmt.getLong(1);

    //do all of your updates/inserts on tables using
new_pkey as a foreign key
    //I like to do this in batches
    Statement stmt = conn.createStatement();
    stmt.addBatch("insert into... )
    stmt.addBatch("update whatever set... )
    stmt.executeBatch ();

conn.commit();

stmt.close();
conn.close();

} catch(SQLException e1) {
    //do something with error 1
    if (conn != null) {
        try {
            conn.rollback();
        } catch(SQLException e2) {
            //do something with error 2
        }
    }
}