code: protected SqlSelect createSourceSelectForDelete(SqlDelete call) {
  		final SqlNodeList selectList = new SqlNodeList(SqlParserPos.ZERO);
  		selectList.add(SqlIdentifier.star(SqlParserPos.ZERO));
  		SqlNode sourceTable = call.getTargetTable();
  		if (call.getAlias() != null) {
  			sourceTable =
  				SqlValidatorUtil.addAlias(
  					sourceTable,
  					call.getAlias().getSimple());
  		}
  		return new SqlSelect(SqlParserPos.ZERO, null, selectList, sourceTable,
  			call.getCondition(), null, null, null, null, null, null);
  	}
docs: Creates the SELECT statement that putatively feeds rows into a DELETE
  statement to be deleted.
  
  @param call Call to the DELETE operator
  @return select statement