[TD-4322]<fix>: taosdemo query then fetch result. (#6211)

* [TD-4322]<fix>: taosdemo query then fetch result.

* build again.
Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

src/kit/taosdemo/taosdemo.c

@@ -1148,7 +1148,6 @@ static int queryDbExec(TAOS *taos, char *command, QUERY_TYPE type, bool quiet) {
 static void appendResultBufToFile(char *resultBuf, char *resultFile)
 {
   FILE *fp = NULL;
-    if (resultFile[0] != 0) {
   fp = fopen(resultFile, "at");
   if (fp == NULL) {
       errorPrint(
@@ -1156,12 +1155,12 @@ static void appendResultBufToFile(char *resultBuf, char *resultFile)
               __func__, __LINE__, resultFile);
       return;
   }
+
   fprintf(fp, "%s", resultBuf);
   tmfclose(fp);
-    }
 }
 
-static void appendResultToFile(TAOS_RES *res, char* resultFile) {
+static void fetchResult(TAOS_RES *res, char* resultFile) {
   TAOS_ROW    row = NULL;
   int         num_rows = 0;
   int         num_fields = taos_field_count(res);
@@ -1179,7 +1178,8 @@ static void appendResultToFile(TAOS_RES *res, char* resultFile) {
 
   // fetch the records row by row
   while((row = taos_fetch_row(res))) {
-    if (totalLen >= 100*1024*1024 - 32000) {
+    if ((resultFile)
+            && (totalLen >= 100*1024*1024 - 32000)) {
         appendResultBufToFile(databuf, resultFile);
         totalLen = 0;
         memset(databuf, 0, 100*1024*1024);
@@ -1194,7 +1194,9 @@ static void appendResultToFile(TAOS_RES *res, char* resultFile) {
 
   verbosePrint("%s() LN%d, databuf=%s resultFile=%s\n",
           __func__, __LINE__, databuf, resultFile);
+  if (resultFile) {
     appendResultBufToFile(databuf, resultFile);
+  }
   free(databuf);
 }
 
@@ -1210,9 +1212,7 @@ static void selectAndGetResult(
         return;
     }
 
-    if ((strlen(pThreadInfo->fp))) {
-      appendResultToFile(res, pThreadInfo->fp);
-    }
+    fetchResult(res, pThreadInfo->fp);
     taos_free_result(res);
 
   } else if (0 == strncasecmp(g_queryInfo.queryMode, "rest", strlen("rest"))) {
@@ -2053,13 +2053,13 @@ static void printfQuerySystemInfo(TAOS * taos) {
 
   // show variables
   res = taos_query(taos, "show variables;");
-  //appendResultToFile(res, filename);
+  //fetchResult(res, filename);
   xDumpResultToFile(filename, res);
 
   // show dnodes
   res = taos_query(taos, "show dnodes;");
   xDumpResultToFile(filename, res);
-  //appendResultToFile(res, filename);
+  //fetchResult(res, filename);
 
   // show databases
   res = taos_query(taos, "show databases;");
@@ -6712,7 +6712,7 @@ static void stable_sub_callback(
   }
 
   if (param)
-    appendResultToFile(res, ((threadInfo *)param)->fp);
+    fetchResult(res, ((threadInfo *)param)->fp);
   // tao_unscribe() will free result.
 }
 
@@ -6725,7 +6725,7 @@ static void specified_sub_callback(
   }
 
   if (param)
-    appendResultToFile(res, ((threadInfo *)param)->fp);
+    fetchResult(res, ((threadInfo *)param)->fp);
   // tao_unscribe() will free result.
 }
 
@@ -6866,13 +6866,13 @@ static void *superSubscribe(void *sarg) {
               sprintf(pThreadInfo->fp, "%s-%d",
                       g_queryInfo.superQueryInfo.result[pThreadInfo->querySeq],
                       pThreadInfo->threadID);
-              appendResultToFile(res, pThreadInfo->fp);
+              fetchResult(res, pThreadInfo->fp);
           }
           if (g_queryInfo.superQueryInfo.result[pThreadInfo->querySeq][0] != 0) {
               sprintf(pThreadInfo->fp, "%s-%d",
                       g_queryInfo.superQueryInfo.result[pThreadInfo->querySeq],
                       pThreadInfo->threadID);
-              appendResultToFile(res, pThreadInfo->fp);
+              fetchResult(res, pThreadInfo->fp);
           }
           consumed[tsubSeq] ++;
 
@@ -6973,7 +6973,7 @@ static void *specifiedSubscribe(void *sarg) {
               sprintf(pThreadInfo->fp, "%s-%d",
                       g_queryInfo.specifiedQueryInfo.result[pThreadInfo->querySeq],
                       pThreadInfo->threadID);
-              appendResultToFile(res, pThreadInfo->fp);
+              fetchResult(res, pThreadInfo->fp);
           }
 
           consumed ++;