if (!handler.hasNext()) {
// Create "SELECT seq_val FROM seq_table WHERE seq_key='table'"
// with database-dependent keyword for lock
// Note: Some databases (InstantDB, HypersonicSQL) don't support such locks.
QueryExpression query = _factory.getQueryExpression();
query.addColumn(_seqTable, _seqValue);
query.addCondition(_seqTable, _seqKey, QueryExpression.OP_EQUALS, JDBCSyntax.PARAMETER);
String lockSQL = query.getStatement(true);
// For the case that "SELECT FOR UPDATE" is not supported, perform dirty checking
String updateSQL = "UPDATE " + _seqTable