Merge pull request #7687 from taosdata/hotfix/TD-6439

[td-6439]fix order by crash issue

src/query/src/qExecutor.c

@@ -5522,7 +5522,9 @@ static SSDataBlock* doSort(void* param, bool* newgroup) {
   }
 
   __compar_fn_t  comp = getKeyComparFunc(pSchema[pInfo->colIndex].type, pInfo->order);
+  if (pInfo->pDataBlock->info.rows) {
     taoscQSort(pCols, pSchema, numOfCols, pInfo->pDataBlock->info.rows, pInfo->colIndex, comp);
+  }
   
   tfree(pCols);
   tfree(pSchema);