code: public final String toSqlOperator(
      final String pOper) throws ExceptionWithCode {
      if ("eq".equals(pOper)) {
        return "=";
      } else if ("ne".equals(pOper)) {
        return "!=";
      } else if ("gt".equals(pOper)) {
        return ">";
      } else if ("gte".equals(pOper)) {
        return ">=";
      } else if ("in".equals(pOper)) {
        return "in";
      } else if ("lt".equals(pOper)) {
        return "<";
      } else if ("lte".equals(pOper)) {
        return "<=";
      } else if ("isnull".equals(pOper)) {
        return "is null";
      } else if ("isnotnull".equals(pOper)) {
        return "is not null";
      } else if ("like".equals(pOper)) {
        return "like";
      } else {
        throw new ExceptionWithCode(ExceptionWithCode.WRONG_PARAMETER,
          "can't match SQL operator: " + pOper);
      }
    }
docs: <p>Make SQL operator e.g. 'eq'-&gt;'&gt;'.</p>
  @param pOper operator - eq, gt, lt
  @return SQL operator
  @throws ExceptionWithCode - code 1003 WRONG_PARAMETER