SelectDesc selDesc = new SelectDesc(false);
List<ExprNodeDesc> colList = new ArrayList<ExprNodeDesc>();
ExprNodeColumnDesc colDesc1 = new ExprNodeColumnDesc(Long.class, "a", "table", false);
ExprNodeColumnDesc colDesc2 = new ExprNodeColumnDesc(Long.class, "b", "table", false);
ExprNodeColumnDesc colDesc3 = new ExprNodeColumnDesc(Long.class, "c", "table", false);
ExprNodeGenericFuncDesc plusDesc = new ExprNodeGenericFuncDesc();
GenericUDF gudf = new GenericUDFOPPlus();
plusDesc.setGenericUDF(gudf);
List<ExprNodeDesc> children = new ArrayList<ExprNodeDesc>();
children.add(colDesc1);
children.add(colDesc2);
plusDesc.setChildren(children);
plusDesc.setTypeInfo(TypeInfoFactory.longTypeInfo);
colList.add(plusDesc);
colList.add(colDesc3);
selDesc.setColList(colList);