[TD-4747]<test>grafana query multi NULL col

tests/script/general/http/grafana_bug.sim

@@ -20,17 +20,22 @@ sql use db
 sql create table tb (ts timestamp, val int, val1 int, val2 int)
 sql create table tb2 (ts timestamp, val int, val1 int, val2 int)
 sql create table t2 (ts timestamp, val int)
+sql create table tb3 (ts timestamp, val int, val1 int, val2 int)
 
 sql insert into tb values('2020-01-01 00:00:00.000', 1, 11, 21)
 sql insert into tb values('2020-01-02 00:00:00.000', 1, 12, 22)
 sql insert into tb values('2020-01-03 00:00:00.000', 2, 13, 23)
 sql insert into tb values('2020-01-04 00:00:00.000', 2, 14, 24)
 
+
 sql insert into tb2 values('2020-01-01 00:00:00.000', 21, 211, 221)
 sql insert into tb2 values('2020-01-02 00:00:00.000', 21, 212, 222)
 sql insert into tb2 values('2020-01-03 00:00:00.000', 22, 213, 223)
 sql insert into tb2 values('2020-01-04 00:00:00.000', 22, 214, 224)
 
+
+sql insert into tb3 values('2020-01-01 00:00:00.000', NULL, NULL, NULL)
+sql insert into tb3 values('2020-01-02 00:00:00.000', NULL, NULL, NULL)
 print ===============  step1 - one query, 1 column, with timestamp
 
 system_content curl -H 'Authorization: Basic cm9vdDp0YW9zZGF0YQ==' -d '[ {"refId":"A","alias":"","sql":"select ts from db.tb where ts >= 1577980800000 "} ]' 127.0.0.1:7111/grafana/query
@@ -235,4 +240,11 @@ if $system_content != @[{"refId":"B","target":"BB{val2:223,}","datapoints":[[213
   return -1
 endi
 
+print ===============  step26 - 2 column, no timestamp, NULL
+system_content curl -H 'Authorization: Basic cm9vdDp0YW9zZGF0YQ==' -d '[ {"refId":"A","alias":"","sql":"select * from db.tb3 "} ]' 127.0.0.1:7111/grafana/query
+print step1-> $system_content
+if $system_content != @[{"refId":"A","target":"{val1:nil, val2:nil}","datapoints":[[null,1577808000000],[null,1577894400000]]}]@ then
+  return -1
+endi
+
 system sh/exec.sh -n dnode1 -s stop -x SIGINT
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