[TD-1961]<fix> modify return when call taos_query()

tests/examples/c/demo.c

@@ -22,6 +22,34 @@
 #include <inttypes.h>
 #include <taos.h>  // TAOS header file
 
+static void queryDB(TAOS *taos, char *command) {
+  int i;
+  TAOS_RES *pSql = NULL;
+  int32_t   code = -1;
+
+  for (i = 0; i < 5; i++) {
+    if (NULL != pSql) {
+      taos_free_result(pSql);
+      pSql = NULL;
+    }
+    
+    pSql = taos_query(taos, command);
+    code = taos_errno(pSql);
+    if (0 == code) {
+      break;
+    }    
+  }
+
+  if (code != 0) {
+    fprintf(stderr, "Failed to run %s, reason: %s\n", command, taos_errstr(pSql));
+    taos_free_result(pSql);
+    taos_close(taos);
+    exit(EXIT_FAILURE);
+  }
+
+  taos_free_result(pSql);
+}
+
 int main(int argc, char *argv[]) {
   TAOS *    taos;
   char      qstr[1024];
@@ -44,22 +72,26 @@ int main(int argc, char *argv[]) {
   printf("success to connect to server\n");
 
 
-  taos_query(taos, "drop database demo");
+  //taos_query(taos, "drop database demo");
+  queryDB(taos, "drop database if exists demo");
 
-  result = taos_query(taos, "create database demo");
-  if (result == NULL) {
-    printf("failed to create database, reason:%s\n", "null result"/*taos_errstr(taos)*/);
-    exit(1);
-  }
+  //result = taos_query(taos, "create database demo");
+  //if (result == NULL) {
+  //  printf("failed to create database, reason:%s\n", "null result"/*taos_errstr(taos)*/);
+  //  exit(1);
+  //}
+  queryDB(taos, "create database demo");
   printf("success to create database\n");
 
-  taos_query(taos, "use demo");
+  //taos_query(taos, "use demo");
+  queryDB(taos, "use demo");
 
   // create table
-  if (taos_query(taos, "create table m1 (ts timestamp, ti tinyint, si smallint, i int, bi bigint, f float, d double, b binary(10))") == 0) {
-    printf("failed to create table, reason:%s\n", taos_errstr(result));
-    exit(1);
-  }
+  //if (taos_query(taos, "create table m1 (ts timestamp, ti tinyint, si smallint, i int, bi bigint, f float, d double, b binary(10))") == 0) {
+  //  printf("failed to create table, reason:%s\n", taos_errstr(result));
+  //  exit(1);
+  //}
+  queryDB(taos, "create table m1 (ts timestamp, ti tinyint, si smallint, i int, bi bigint, f float, d double, b binary(10))");
   printf("success to create table\n");
 
   // sleep for one second to make sure table is created on data node
@@ -80,8 +112,10 @@ int main(int argc, char *argv[]) {
       printf("insert row: %i\n", i);
     } else {
       printf("failed to insert row: %i, reason:%s\n", i, "null result"/*taos_errstr(result)*/);
+      taos_free_result(result);
       exit(1);
     }
+    taos_free_result(result);
 
     //sleep(1);
   }
@@ -91,7 +125,8 @@ int main(int argc, char *argv[]) {
   sprintf(qstr, "SELECT * FROM m1");
   result = taos_query(taos, qstr);
   if (result == NULL || taos_errno(result) != 0) {
-    printf("failed to select, reason:%s\n", taos_errstr(result));
+    printf("failed to select, reason:%s\n", taos_errstr(result));    
+    taos_free_result(result);
     exit(1);
   }