[td-1067] fix bugs in lastrow query.

src/query/src/qExecutor.c

@@ -5262,7 +5262,7 @@ static void stableQueryImpl(SQInfo *pQInfo) {
   int64_t st = taosGetTimestampUs();
 
   if (QUERY_IS_INTERVAL_QUERY(pQuery) ||
-      (isFixedOutputQuery(pRuntimeEnv) && (!isPointInterpoQuery(pQuery)) && !pRuntimeEnv->groupbyNormalCol)) {
+      (isFixedOutputQuery(pRuntimeEnv) && (!isPointInterpoQuery(pQuery)) && (!pRuntimeEnv->groupbyNormalCol))) {
     multiTableQueryProcess(pQInfo);
   } else {
     assert((pQuery->checkBuffer == 1 && pQuery->intervalTime == 0) || isPointInterpoQuery(pQuery) ||

src/tsdb/src/tsdbRead.c

@@ -301,6 +301,9 @@ TsdbQueryHandleT tsdbQueryLastRow(TSDB_REPO_T *tsdb, STsdbQueryCond *pCond, STab
   pCond->order = TSDB_ORDER_DESC;
   pCond->twindow = changeTableGroupByLastrow(groupList);
 
+  //descending order query, skey >= ekey
+  SWAP(pCond->twindow.skey, pCond->twindow.ekey, TSKEY);
+
   STsdbQueryHandle *pQueryHandle = (STsdbQueryHandle*) tsdbQueryTables(tsdb, pCond, groupList, qinfo);
   return pQueryHandle;
 }