refactor some codes, avoid set return code to be 0.

src/client/src/tscLocal.c

@@ -445,7 +445,8 @@ void tscSetLocalQueryResult(SSqlObj *pSql, const char *val, const char *columnNa
   SSqlRes *pRes = &pSql->res;
 
   pCmd->numOfCols = 1;
-  SQueryInfo* pQueryInfo = tscGetQueryInfoDetail(pCmd, 0);
+  
+  SQueryInfo* pQueryInfo = tscGetQueryInfoDetail(pCmd, pCmd->clauseIndex);
   pQueryInfo->order.order = TSQL_SO_ASC;
   
   tscClearFieldInfo(&pQueryInfo->fieldsInfo);

src/client/src/tscUtil.c

@@ -365,6 +365,9 @@ void tscFreeSqlCmdData(SSqlCmd* pCmd) {
   tscFreeSubqueryInfo(pCmd);
 }
 
+/*
+ * this function must not change the pRes->code value, since it may be used later.
+ */
 void tscFreeResData(SSqlObj* pSql) {
   SSqlRes* pRes = &pSql->res;
   
@@ -386,10 +389,8 @@ void tscFreeResData(SSqlObj* pSql) {
   
   pRes->offset = 0;
   pRes->useconds = 0;
-  pRes->code = 0;
   
   pRes->data = NULL;
-  
   tfree(pRes->pGroupRec);
   
   tscDestroyLocalReducer(pSql);
@@ -404,8 +405,6 @@ void tscFreeSqlObjPartial(SSqlObj* pSql) {
   }
 
   SSqlCmd* pCmd = &pSql->cmd;
-  SSqlRes* pRes = &pSql->res;
-
   STscObj* pObj = pSql->pTscObj;
 
   int32_t cmd = pCmd->command;