test: refine query cases

tests/script/tsim/parser/interp.sim

@@ -68,12 +68,8 @@ print ================= TD-5931
 sql create stable st5931(ts timestamp, f int) tags(t int)
 sql create table ct5931 using st5931 tags(1)
 sql create table nt5931(ts timestamp, f int)
-sql select interp(*) from nt5931 where ts=now
-sql select interp(*) from st5931 where ts=now
-sql select interp(*) from ct5931 where ts=now
-
-if $rows != 0 then
-  return -1
-endi
+sql_error select interp(*) from nt5931 where ts=now
+sql_error select interp(*) from st5931 where ts=now
+sql_error select interp(*) from ct5931 where ts=now
 
 system sh/exec.sh -n dnode1 -s stop -x SIGINT