public void SaveChanges(Entity entity) throws Exception {
    //  do we need to do anything?
    if (entity.getIsNew()) this.Insert(entity);
    else if (entity.getIsModified()) this.Update(entity);
    else if (entity.getIsDeleted()) this.Delete(entity);

    // nothing to do...
  }
  private SqlStatement GetInsertStatement(Entity entity) throws Exception {
    StringBuffer builder = new StringBuffer();
    SqlStatement sql = new SqlStatement();

    // et...
    EntityType et = getEntityType();

    // create...
    builder.append("INSERT INTO ");
    builder.append(et.getNativeName());
    builder.append(" (");
    boolean first = true;
    for (int index = 0; index < et.getFields().size(); index++) {
      EntityField field = (EntityField) et.getFields().elementAt(index);
      if (entity.getIsModified(field)) {
        if (first) first = false;
        else builder.append(", ");
        builder.append(field.getNativeName());
      }
    }
    builder.append(") VALUES (");
    first = true;
    for (int index = 0; index < et.getFields().size(); index++) {
      EntityField field = (EntityField) et.getFields().elementAt(index);
      if (entity.getIsModified(field)) {
        if (first) first = false;
        else builder.append(", ");
        builder.append("?");

        // add in the parameter....
        sql.AddParameterValue(entity.GetValue(field));
      }
    }
    builder.append(")");

    // return...
    sql.setCommandText(builder.toString());
    return sql;
  }
  private SqlStatement GetUpdateStatement(Entity entity) throws Exception {
    StringBuffer builder = new StringBuffer();
    SqlStatement sql = new SqlStatement();

    // et...
    EntityType et = getEntityType();

    // update...
    builder.append("UPDATE ");
    builder.append(et.getNativeName());
    builder.append(" SET ");

    // walk...
    boolean first = true;
    EntityField key = null;
    for (int index = 0; index < et.getFields().size(); index++) {
      EntityField field = (EntityField) et.getFields().elementAt(index);
      if (field.getIsKey()) key = field;
      else if (entity.getIsModified(field)) {
        if (first) first = false;
        else builder.append(", ");

        // add the snippet...
        builder.append(field.getNativeName());
        builder.append("=?");

        // add the parameter...
        Object value = entity.GetValue(field);
        sql.AddParameterValue(value);
      }
    }

    // append...
    AppendIdConstraint(builder, sql, key, entity);

    // return...
    sql.setCommandText(builder.toString());
    return sql;
  }