diff --git a/examples/c/demoapi.c b/examples/c/demoapi.c
index c3a6d267766dcb5621c126fb1dc3d411f9f3929a..88d924e97c46b6c089c01e8fbcc39a26fe6dcde7 100644
--- a/examples/c/demoapi.c
+++ b/examples/c/demoapi.c
@@ -74,7 +74,12 @@ static void prepare_data(TAOS* taos) {
     res = taos_query(taos, "create database test;");
     taos_free_result(res);
     taosMsleep(100);
-    taos_select_db(taos, "test");
+    if (taos_select_db(taos, "test")) {
+        errorPrint("%s() LN%d: error no: %d, reason: %s\n",
+                __func__, __LINE__, taos_errno(res), taos_errstr(res));
+        taos_free_result(res);
+        return;
+    }
 
     char command[1024] = {0};
     sprintf(command, "%s", "create table meters(ts timestamp, f float, n int, bin1 binary(20), c nchar(20), bin2 binary(20)) tags(area int, city binary(20), dist nchar(20), street binary(20));");