Method merge

src/java/simpledb/storage/TupleDesc.java:205–212

Merge two TupleDescs into one, with td1.numFields + td2.numFields fields, with the first td1.numFields coming from td1 and the remaining from td2. @param td1 The TupleDesc with the first fields of the new TupleDesc @param td2 The TupleDesc with the last fields of the TupleDesc

(TupleDesc td1, TupleDesc td2)

     * @return the new TupleDesc
     */
    public static TupleDesc merge(TupleDesc td1, TupleDesc td2) {
        // some code goes here
        List<TDItem> tupleDescList01 = td1.tupleDescList;
        List<TDItem> tupleDescList02 = td2.tupleDescList;
        List<TDItem> res = new ArrayList<>(tupleDescList01);
        res.addAll(tupleDescList02);
        return new TupleDesc(res);
    }

    /**
     * 比较type