[TD-11983]<fix>: elapsed function second param time_unit should not contain now keyword

src/client/src/tscSQLParser.c

@@ -2852,6 +2852,10 @@ int32_t addExprAndResultField(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t col
         char val[8] = {0};
 
         int64_t tickPerSec = 0;
+        if (pParamElem[1].pNode->exprToken.type == TK_NOW) {
+          return invalidOperationMsg(tscGetErrorMsgPayload(pCmd), msg2);
+        }
+
         if ((TSDB_DATA_TYPE_NULL == pParamElem[1].pNode->value.nType) || tVariantDump(&pParamElem[1].pNode->value, (char*) &tickPerSec, TSDB_DATA_TYPE_BIGINT, true) < 0) {
           return TSDB_CODE_TSC_INVALID_OPERATION;
         }