[TD-5618]<fix> fix distinct(tbname) error

src/query/src/qExecutor.c

@@ -6661,19 +6661,20 @@ static SSDataBlock* hashDistinct(void* param, bool* newgroup) {
       if (isNull(val, type)) {
         continue;
       }
-
+      char* p = val;
       size_t keyLen = 0;
       if (IS_VAR_DATA_TYPE(pOperator->pExpr->base.colType)) {
         tstr* var = (tstr*)(val);
+        p = var->data;
         keyLen = varDataLen(var);
       } else {
         keyLen = bytes;
       }
 
       int dummy;
-      void* res = taosHashGet(pInfo->pSet, val, keyLen);
+      void* res = taosHashGet(pInfo->pSet, p, keyLen);
       if (res == NULL) {
-        taosHashPut(pInfo->pSet, val, keyLen, &dummy, sizeof(dummy));
+        taosHashPut(pInfo->pSet, p, keyLen, &dummy, sizeof(dummy));
         char* start = pResultColInfoData->pData + bytes * pInfo->pRes->info.rows;
         memcpy(start, val, bytes);
         pRes->info.rows += 1;